Method of reducing fraud in connection with employment, public license applications, social security, food stamps, welfare or other government benefits

• US 5,224,173 A
• Filed: 10/29/1991
• Issued: 06/29/1993
• Est. Priority Date: 10/29/1991
• Status: Expired due to Fees

• Current Assignee: Avant, Inc. (Sentinel Solutions, Inc.)
• Original Assignee: Robert L. Nathans, Roger J. Kuhns
• Inventors: Nathans, Robert L., Kuhns, Roger J.
• Primary Examiner(s): Moore, David K.
• Assistant Examiner(s): Stellrecht, Barry
• Application Number:
  US07/783,867
• Time in Patent Office: 609 Days
• Field of Search: 382/2, 382/4, 382/37, 382/38, 340/825.33, 340/825.34
• US Class Current: 382/116
• CPC Class Codes: G06V 40/12 Fingerprints or palmprints
• CPC Class Codes: G07C 9/37 using biometric data, e.g. fingerprints, iris scans or voice recognition

Abstract

A current applicant for a government benefit presents a fingerprint signature to a large data bank to determine if his signature is already in the data bank, to thus indicate fraud. His fingerprint is rapidly machine correlated with the fingerprints of prior approved applicants and a number of close matches are thereafter visually examined by a human operator to definitively determine whether the current applicant'"'"'s fingerprint is already in the data bank. However, a coarse biometric index (CBI) of the current applicant is first compared with all CBIs of approved applicants and only a tiny percentage of positive CBI matches result in the correlation of fingerprints and visual examination by the human operator, thereby to save huge amounts of human matching time and cost. The result is reliable and economical scanning of huge data banks such as the Social Security data base. The CBI can display facial images and eliminate fingerprints altogether if desired.

Claims

1. A method of employing an electronically controlled data processor for determining whether a currently processed person under examination should be extended a privilege granted by society comprising the steps of:

(a) inserting refined biometric signatures of numerous approved applicants for said privilege within said electronically controlled data processor;

(b) producing a currently processed refined biometric signature of a current applicant for said privilege;

(c) comparing said currently processed refined biometric signature of said current applicant for said privilege with refined biometric signatures of approved applicants stored within said data processor;

(d) producing close match signals upon the production of a close match of said currently processed refined biometric signature with refined biometric signatures stored within said data processor;

(e) producing tentative applicant reject signals in response to the production of said positive close match signals;

(f) generating human recognizable representations of those closely matched refined biometric signatures which produced said tentative application reject signals for enabling comparison by a human being, thereby to tend to eliminate the effect of false positive match signals which tend to increase with large data banks, and which could result in an erroneous withholding of a privilege which could be otherwise extended to said applicant;

(g) producing a coarse biometric index for each approved applicant, said coarse biometric index being indicative of different types of coarse biometric characteristics;

(h) inserting coarse biometric indexes of approved applicants into said data processor;

(i) comparing a coarse biometric index of a current applicant with numerous coarse biometric indexes of approved applicants stored within said data bank;

(j) producing a negative comparison signal upon a mismatch resulting from executing step (i);

(k) omitting steps (c)-(f) in response to the production of said negative comparison signal, thereby to save substantial processing labor which would otherwise be required; and

(l) wherein the coarse biometric indexes compared in accordance with step (i) are representations of a plurality of different types of coarse biometric characteristics of persons matched, at least some of which are selected from the group consisting of sex, age, eye color, hair color, complexion, height, weight, facial feature parameters, slant of handwriting and handwriting readability.

2. The method of claim 1 wherein said coarse biometric indexes are represented by digital words, thereby to enable high speed comparisons of said coarse biometric indexes.

3. The method of claim 2 further including

(l) inserting additional facial image indicia of approved applicants into said electronically controlled data bank;

(m) generating additional facial image indicia of each current applicant;

(n) in response to the production of a tentative applicant reject signal produced in accordance with step (e), displaying to a processing clerk facial image indicia of a current applicant produced in accordance with step (m) and facial image indicia within said data bank associated with approved applicants matched with said current applicant in accordance with steps (c) and (d), thereby to further tend to eliminate false positive match signals.

4. The method of claim 1 further including

(l) inserting additional facial image indicia of approved applicants into said electronically controlled data processor;

(m) generating additional facial image indicia of each current applicant;

(n) in response to the production of a tentative applicant reject signal produced in accordance with step (e), displaying to a processing clerk facial image indicia of a current applicant produced in accordance with step (m) and facial image indicia within said data bank associated with approved applicants matched with said current applicant in accordance with steps (c) and (d), thereby to further tend to eliminate false positive match signals.

5. The method of claim 1 wherein said coarse biometric index comprises several sub-indexes and further including the step of selectively reducing the number of sub-indexes effectively compared in accordance with step (i) in order to decrease the number of coarse biometric mismatch signals to in turn increase the number of refined biometric signatures to be examined for examinations of greater importance.

6. The method of claim 1 wherein said refined biometric signatures are selected from the group consisting of fingerprints, facial images, voiceprints, palm prints, retinal patterns and vein patterns.

7. The method of claim 1 wherein step (f) includes displaying to a human operator a facial image retrieved from said electronically controlled data processor in accordance with step (e).

8. A method of employing an electronically controlled data processor for determining whether a currently processed person under examination should be extended a privilege granted by society comprising the steps of:

(a) inserting refined biometric signatures of numerous approved applicants for said privilege within said electronically controlled data processor;

(b) producing a currently processed refined biometric signature of a current applicant for said privilege;

(c) comparing said currently processed refined biometric signature of said current applicant for said privilege with refined biometric signatures of approved applicants stored within said data processor;

(d) producing close match signals upon the production of a close match of said currently processed refined biometric signature with refined biometric signatures stored within said data processor;

(e) producing tentative applicant reject signals in response to the production of said positive close match signals;

(f) generating human recognizable representations of those closely matched refined biometric signatures which produced said tentative application reject signals for enabling comparison by a human being, thereby to tend to eliminate the effect of false positive match signals which tend to increase with large data banks, and which could result in an erroneous withholding of a privilege which could be otherwise extended to said applicant;

(g) producing a coarse biometric index for each approved applicant, said coarse biometric index being indicative of different types of coarse biometric characteristics;

(h) inserting coarse biometric indexes of approved applicants into said data processor;

(i) comparing a coarse biometric index of a current applicant with numerous coarse biometric indexes of approved applicants stored within said data bank;

(j) producing a negative comparison signal upon a mismatch resulting from executing step (i);

(k) omitting steps (c)-(f) in response to the production of said negative comparison signal, thereby to save substantial processing labor which would otherwise be required; and

(l) wherein said coarse biometric index comprises several sub-indexes and further including the step of selectively reducing the number of sub-indexes effectively compared in accordance with step (i) in order to decrease the number of coarse biometric mismatch signals to in turn increase the number of refined biometric signatures to be examined for examinations of greater importance.

9. A method of employing an electronically controlled data processor for thwarting cheaters from obtaining multiple government benefits comprising the steps of:

(a) inserting refined biometric signatures of numerous approved applicants for said government benefits within said electronically controlled data processor serving a protected area including a plurality of government benefit issue stations;

(b) producing currently processed refined biometric signatures of current applicants applying for said government benefits at said plurality of issue stations within said protected area;

(c) comparing a currently processed refined biometric signature of each current applicant for said government benefits with said refined biometric signatures of numerous approved applicants stored within said electronically controlled data processor;

(d) producing close match signals upon the occurrence of a close match between each currently processed refined biometric signature with refined biometric signatures of approved applicants stored within said electronically controlled data processor;

(e) utilizing said close match signals to tentatively reject an application for said government benefits by a current applicant;

(f) recording digital words representing a coarse biometric index for each approved applicant within said data bank, said coarse biometric index being indicative of a plurality of different types of physical biometric characteristics shared in common with other approved applicants;

(g) producing a coarse biometric index of a current applicant for government benefits;

(h) comparing the coarse biometric index of said current applicant for government benefits with coarse biometric indexes of approved applicants stored within said electronically controlled data processor;

(i) producing a negative comparison signal in response to a coarse biometric index mismatch resulting from the execution of step (h); and

(j) omitting steps (c)-(e) in response to the production of each negative comparison signal, thereby to save substantial application processing time which would otherwise be required; and

(k) wherein said coarse biometric index comprises several sub-indexes and further including the step of selectively reducing the number of sub-indexes effectively compared in accordance with step (h) in order to decrease the number of coarse biometric mismatch signals to in turn increase the number of refined biometric signatures to be examined for examinations of greater importance.

10. A method of employing an electronically controlled data processor for thwarting cheaters from obtaining multiple government benefits comprising the steps of:

(a) inserting refined biometric signatures of numerous approved applicants for said government benefits within said electronically controlled data processor serving a protected area including a plurality of government benefit issue stations;

(b) producing currently processed refined biometric signatures of current applicants applying for said government benefits at said plurality of issue stations within said protected area;

(c) comparing a currently processed refined biometric signature of each current applicant for said government benefits with said refined biometric signatures of numerous approved applicants stored within said electronically controlled data processor;

(d) producing close match signals upon the occurrence of a close match between each currently processed refined biometric signature with refined biometric signatures of approved applicants stored within said electronically controlled data processor;

(e) utilizing said close match signals to tentatively reject an application for said government benefits by a current applicant;

(f) recording digital words representing a coarse biometric index for each approved applicant within said data bank, said coarse biometric index being indicative of a plurality of different types of physical biometric characteristics shared in common with other approved applicants;

(g) producing a coarse biometric index of a current applicant for government benefits;

(h) comparing the coarse biometric index of said current applicant for government benefits with coarse biometric indexes of approved applicants stored within said electronically controlled data processor;

(i) producing a negative comparison signal in response to a coarse biometric index mismatch resulting from the execution of step (h); and

(j) omitting steps (c)-(e) in response to the production of each negative comparison signal, thereby to save substantial application processing time which would otherwise be required; and

(k) further including the step of producing spot check signals at random intervals during processing of current applicants for said government benefit and causing steps (c)-(e) to be carried out only in response to a spot check signal associated with particular randomly selected current applicants, thereby to reduce processing times.

11. The method of claim 10 wherein step (k) is not carried out if data is produced at an issue station indicating that the current applicant'"'"'s demeanor is suspicious or that the current applicant states that he/she is over the age of twenty-five and that he/she has never worked or that the address he/she gives indicates that he/she resides in a middle or upper income bracket town regardless of age.

12. A method of employing an electronically controlled data processor for thwarting cheaters from obtaining multiple government benefits comprising the steps of:

(a) inserting refined biometric signatures of numerous approved applicants for said government benefits within a large electronically controlled data bank serving a protected area including a plurality of government benefit issue stations;

(b) producing currently processed refined biometric signatures of current applicants applying for said government benefits at said plurality of issue stations within said protected area;

(c) comparing currently processed refined biometric signatures of current applicants for said government benefits with said refined biometric signatures of numerous approved applicants stored within said large electronically controlled data bank;

(d) producing close match signals upon the occurrence of a close match between each currently processed refined biometric signature with numerous refined biometric signatures of approved applicants stored within said data bank;

(e) utilizing said close match signals to reject an application for said government benefits by said current applicant;

(f) recording a coarse biometric index for each approved applicant within said data processor, said coarse biometric index being indicative of a plurality of different types of coarse biometric characteristics;

(g) comparing the coarse biometric index of said current applicant for government benefits with coarse biometric indexes of approved applicants stored within said data processor;

(h) producing a negative comparison signal in response to a coarse biometric mismatch resulting from the execution of step (g);

(i) omitting steps (c)-(e) in response to the production of each negative comparison signal, thereby to save application processing time which would otherwise be required;

(j) and wherein said coarse biometric index comprises several sub-indexes and further including the step of selectively reducing the number of sub-index effectively compared in accordance with step (g) in order to decrease the number of coarse biometric mismatch signals to in turn increase the number of refined biometric signatures to be examined for examinations of greater importance.

13. A method of employing an electronically controlled data processor for thwarting cheaters from obtaining multiple government benefits comprising the steps of:

(a) inserting refined biometric signatures of numerous approved applicants for said government benefits within a large electronically controlled data processor serving a protected area including a plurality of government benefit issue stations;

(b) producing currently processed refined biometric signatures of current applicants applying for said government benefits at said plurality of issue stations within said protected area;

(c) comparing currently processed refined biometric signatures of current applicants for said government benefits with said refined biometric signatures of numerous approved applicant stored within said large data electronically controlled data processor;

(d) producing close match signals upon the occurrence of a close match between each currently processed refined biometric signature with numerous refined biometric signatures of approved applicants stored within said data processor;

(e) utilizing said close match signals to reject an application for said government benefits by said current applicant; and

(f) further including the step of producing spot check signals at random intervals during processing of current applicants for said government benefit and causing steps (c)-(e) to be carried out only in response to a spot check signal associated with particularly randomly selected current applicants, thereby to reduce processing times.

14. The method of claim 13 wherein step (f) is not carried out if data is produced at an issue station indicating that the current applicant'"'"'s demeanor is suspicious or that the current applicant states that he is over the age of twenty five and that he has never worked or that the address he gives indicates that he resides in a middle or upper income bracket town regardless of age.

15. A method of employing an electronically controlled data processor for determining whether a currently processed person under examination should be extended a privilege granted by society comprising the steps of:

(a) recording a coarse biometric signature and a refined biometric signature for each previously processed person within a large electronically controlled data processor;

(b) transmitting to said electronically controlled data processor a currently processed coarse biometric signature and a refined biometric signature of a currently processed person;

(c) addressing said electronically controlled data processor with a coarse biometric signature of a currently processed person under examination;

(d) comparing said currently processed coarse biometric signature with numerous coarse biometric signatures of previously processed persons stored within said electronically controlled data processor and producing a coarse biometric match signal upon the detection of a coarse biometric signature match;

(e) in response to the production of a coarse biometric match signal in accordance with step (d), comparing said refined biometric signature of said currently processed person with a presently addressed refined biometric signature of a previously processed person stored in said electronically controlled data processor and producing a refined biometric signature close match signal upon the detection of a close refined biometric signature match;

(f) following the production of said refined biometric signature close match signal, generating a human recognizable representation of those refined biometric signatures which produced refined biometric signature close match signals in accordance with step (e) for enabling comparison thereof by a human being, thereby to eliminate the effect of false positive refined biometric signature match signals which tend to increase with large data banks, and which could result a rejection of said applicant who may be entitled to said privilege;

(g) should a coarse biometric positive match signal not be produced in accordance with step (d), omitting steps (e) and (f) and now comparing said currently processed coarse biometric signature with a next coarse biometric signature stored within said electronically controlled data processor of a next previously processed person, thereby to save substantial amounts of processing times;

(h) repeating steps (b)-(g) for a next currently processed coarse biometric signature of a next currently processed person; and

(i) wherein said coarse biometric signature comprises several coarse biometric sub-signatures and further including the step of selectively reducing the number of sub-signatures effectively compared in accordance with step (d) in order to decrease the number of coarse biometric mismatch signals to in turn increase the number of refined biometric signatures to be examined for examinations of greater importance.

16. A method of employing an electronically controlled data processor for determining whether a currently processed person under examination should be extended a privilege granted by society comprising the steps of:

(a) recording a coarse biometric signature and a refined biometric signature for each previously processed person within a electronically controlled data processor;

(b) transmitting to said data processor a currently processed coarse biometric signature and a refined biometric signature of a currently processed person;

(c) addressing said data processor with a coarse biometric signature of a currently processed person under examination;

(d) comparing said currently processed coarse biometric signature with numerous coarse biometric signatures of previously processed persons stored within said data processor and producing a coarse biometric match signal upon the detection of a coarse biometric signature match;

(e) in response to the production of a coarse biometric match signal in accordance with step (d), comparing said refined biometric signature of said currently processed person with a presently addressed refined biometric signature of a previously processed person stored in said data processor and producing a refined biometric signature close match signal upon the detection of a close refined biometric signature match;

(f) following the production of said refined biometric signature close match signal, generating a human recognizable representation of those refined biometric signatures which produced refined biometric signature close match signals in accordance with step (e) for enabling comparison thereof by a human being, thereby to eliminate the effect of false positive refined biometric signature match signals which tend to increase with large data banks, and which could result in an erroneous rejection of said applicant;

(g) should a coarse biometric positive match signal not be produced in accordance with step (d), omitting steps (e) and (f) and now comparing said currently processed coarse biometric signature with a next coarse biometric signature stored within said data bank of a next previously processed person, thereby to save substantial amounts of processing times; and

(h) repeating steps (b)-(g) for a next currently processed coarse biometric signature of a next currently processed person; and

wherein the coarse biometric signatures compared in accordance with step (d) are representations of several coarse biometric characteristics of persons matched, at least some of which are selected from the group consisting of sex, age, eye color, hair color, complexion, height, weight, facial feature parameters, slant of handwriting and handwriting readability.

17. A method of employing an electronically controlled data processor for determining whether a currently processed person under examination should be extended a privilege granted by society comprising the steps of:

(a) recording a coarse biometric signature and a refined biometric signature for each previously processed person within said large electronically controlled data processor;

(b) transmitting to said data processor a currently processed coarse biometric signature and a refined biometric signature of a currently processed person;

(c) addressing said data processor with a coarse biometric signature of a currently processed person under examination;

(d) comparing said currently processed coarse biometric signature with numerous coarse biometric signatures of previously processed persons stored within said large data processor and producing a coarse biometric match signal upon the detection of a coarse biometric signature match;

(e) in response to the production of a coarse biometric match signal in accordance with step (d), comparing said refined biometric signature of said currently processed person with a presently addressed refined biometric signature of a previously processed person stored in said data processor and producing a refined biometric signature close match signal upon the detection of a close refined biometric signature match;

(f) following the production of said refined biometric signature close match signal, generating a human recognizable representation of those refined biometric signatures which produced refined biometric signature close match signals in accordance with step (e) for enabling comparison thereof by a human being, thereby to eliminate the effect of false positive refined biometric signature match signals which tend to increase with large data banks, and which could result in an erroneous rejection of said applicant;

(g) should a coarse biometric positive match signal not be produced in accordance with step (d), omitting steps (e) and (f) and now comparing said currently processed coarse biometric signature with a next coarse biometric signature stored within said data processor of a next previously processed person, thereby to save substantial amounts of processing times;

(h) repeating steps (b)-(g) for a next currently processed coarse biometric signature of a next currently processed person;

(i) and wherein said coarse biometric signatures are represented by digital words and step (d) includes comparing said digital words in order to determine the presence of a positive match therebetween, thereby to enable high speed comparison of the coarse biometric signatures.

18. The method of claim 17 wherein step (f) includes producing a visual display of images of refined biometric signatures for visual examination by said human operator to determine the presence of a definitive match.

19. The method of claim 18 wherein said visual display includes a pair of facial images, and wherein the coarse biometric signatures compared in accordance with step (d) are representations of several coarse biometric characteristics of persons matched, at least some of which are selected from the group consisting of sex, age, eye color, hair color, complexion, height, weight, facial feature parameters, slant of handwriting and handwriting readability.

20. A method of employing an electronically controlled data processor for thwarting cheaters from obtaining multiple government benefits comprising the steps of:

(a) inserting refined biometric signatures of approved applicants for said government benefits within a large electronically controlled data bank, which data bank is divided into a plurality of sub-banks, each serving to protect a given protected geographical area;

(b) producing a currently processed refined biometric signature of a particular current applicant for a government benefit;

(c) addressing a particular data sub-bank with said currently processed refined biometric signature of said particular applicant;

(d) comparing said currently processed refined biometric signature of said particular applicant with refined biometric signatures of prior applicants stored within said particular data sub-bank;

(e) producing a definitive positive match signal upon definitive matching of said currently processed refined biometric signature with a refined biometric signature stored within said data sub-bank;

(f) producing an application reject signal in response to the production of said definitive positive match signal;

(g) entering the currently processed refined biometric signature of said particular person under examination which produced said definitive positive match signal in a data sub-bank reject store associated with said particular data sub-bank; and

(h) additionally recording said refined biometric signature which produced said definitive positive match signal in other reject stores associated with data sub-banks other than said particular data sub-bank, thereby to tend to prevent said particular applicant from fraudulently obtaining multiple government benefits by applying within geographical areas protected by said other data sub-banks.

21. The method of claim 20 wherein said large data bank receives, in accordance with step (a) refined biometric signatures from issue stations located throughout an entire country and each data sub-bank receives, in accordance with step (c), refined biometric signatures from issue stations located within protected geographical areas representing a substantial fraction of said entire country.

22. A method of employing an electronically controlled data processor for determining whether a currently processed person under examination should be extended a privilege granted by society comprising the steps of:

(a) inserting into said electronically controlled data processor coarse biometric indexes of previously processed persons, each coarse biometric index representing a plurality of various different types of coarse biometric characteristics, and additionally inserting refined biometric signatures of previously processed persons representing refined biometric characteristics which tend to discriminate one person from the other in a more definitive manner than the coarse biometric characteristics;

(b) producing a currently processed coarse biometric index of a currently processed person;

(c) comparing said currently processed coarse biometric index of said currently processed person with numerous coarse biometric indexes of previously processed persons stored within said data processor;

(d) producing coarse biometric index match signals upon matching of said currently processed coarse biometric index with coarse biometric indexes of previously processed persons stored within said data processor;

(e) in response to the production of said coarse biometric index match signals, comparing a refined biometric signature of a currently processed person with refined biometric signatures of those previously processed persons which produced coarse biometric index match signals in accordance with step (d) in order to determine whether said currently processed person is the same person as a previously processed person; and

(f) wherein the coarse biometric index compared in accordance with step (c) are each representations of several coarse biometric characteristics of persons being compared, at least some of which are selected from the group consisting of sex, age, eye color, hair color, complexion, height, weight, facial feature ratios, slant of handwriting and handwriting readability.

23. The method of claim 22 wherein said coarse biometric signatures are represented by an index word comprising several sub-indexes and further including the step of reducing, from time to time, the number of sub-indexes effectively compared in accordance with step (c) in order to decrease the number of coarse biometric mismatch signals to in turn increase the number of refined biometric signatures to be examined for examinations of greater importance.

24. The method of claim 22 wherein said coarse biometric signatures are represented by digital words, thereby to enable high speed comparisons of said coarse biometric indexes.

25. The method of claim 22 wherein step (e) includes displaying to a human operator a facial image retrieved from said electronically controlled data processor in accordance with step (e).

30. The method of claim 24 wherein step (e) includes displaying to a human operator a facial image retrieved from said electronically controlled data processor in accordance with step (e).

26. A method of employing an electronically controlled data processor for determining whether a currently processed person under examination should be extended a privilege granted by society comprising the steps of:

(a) inserting into said electronically controlled data processor coarse biometric indexes of previously processed persons, each coarse biometric index representing a plurality of various different types of coarse biometric characteristics, and additionally inserting refined biometric signatures of previously processed persons representing refined biometric characteristics which tend to discriminate one person from the other in a more definitive manner than the coarse biometric characteristics;

(b) producing a currently processed coarse biometric index of a currently processed person;

(c) comparing said currently processed coarse biometric index of said currently processed person with numerous coarse biometric indexes of previously processed persons stored within said data processor;

(d) producing coarse biometric index match signals upon matching of said currently processed coarse biometric index with coarse biometric indexes of previously processed persons stored within said data processor;

(e) in response to the production of said coarse biometric index match signals, comparing a refined biometric signature of a currently processed person with refined biometric signatures of those previously processed persons which produced coarse biometric index match signals in accordance with step (d) in order to determine whether said currently processed person is the same person as a previously processed person; and

(f) wherein said coarse biometric indexes are represented by an index word comprising several sub-indexes and further including the step of reducing, from time to time, the number of sub-indexes effectively compared in accordance with step (c) in order to decrease the number of coarse biometric mismatch signals to in turn increase the number of refined biometric signatures to be examined for examinations of greater importance.

27. The method of claim 26 wherein said coarse biometric signatures are represented by digital words, thereby to enable high speed comparisons of said coarse biometric indexes.

28. The method of claim 26 wherein step (e) includes displaying to a human operator a facial image retrieved from said electronically controlled data processor in accordance with step (e).

29. A method of employing an electronically controlled data processor for determining whether a currently processed person under examination should be extended a privilege granted by society comprising the steps of:

(a) inserting into said electronically controlled data processor coarse biometric indexes of previously processed persons, each coarse biometric index representing a plurality of various different types of coarse biometric characteristics, and additionally inserting refined biometric signatures of previously processed persons representing refined biometric characteristics which tend to discriminate one person from the other in a more definitive manner than the coarse biometric characteristics;

(b) producing a currently processed coarse biometric index of a currently processed person;

(c) comparing said currently processed coarse biometric index of said currently processed person with numerous coarse biometric indexes of previously processed persons stored within said data processor;

(d) producing coarse biometric index match signals upon matching of said currently processed coarse biometric index with coarse biometric indexes of previously processed persons stored within said data processor;

(e) in response to the production of said coarse biometric index match signals, comparing a refined biometric signature of a currently processed person with refined biometric signatures of those previously processed persons which produced coarse biometric index match signals in accordance with step (d) in order to determine whether said currently processed person is the same person as a previously processed person; and

(f) wherein step (e) is carried out by human visual inspection; and

wherein said coarse biometric indexes are represented by an index word comprising several sub-indexes and further including the step of reducing, from time to time, the number of sub-indexes effectively compared in accordance with step (c) in order to decrease the number of coarse biometric mismatch signals to in turn increase the number of refined biometric signatures to be examined for examinations of greater importance.