BPR for Limited Examinations

OSAC 2021-N-0020

Best Practice

Recommendations for

Limited Examinations

Friction Ridge Subcommittee

Physics/Pattern Scientific Area Committee

Organization of Scientific Area Committees (OSAC) for Forensic Science

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BPR for Limited Examinations

Draft OSAC Proposed Standard

OSAC 2021-N-0020

Best Practice Recommendations for

Limited Examinations

Prepared by

Friction Ridge Subcommittee

Version: 1.0

May 4, 2021

Disclaimer:

This OSAC Proposed Standard was written by the Friction Ridge Subcommittee of the

Organization of Scientific Area Committees (OSAC) for Forensic Science following a process

that includes an open comment period. This Proposed Standard will be submitted to a standards

developing organization and is subject to change.

There may be references in an OSAC Proposed Standard to other publications under

development by OSAC. The information in the Proposed Standard, and underlying concepts and

methodologies, may be used by the forensic-science community before the completion of such

companion publications.

Any identification of commercial equipment, instruments, or materials in the Proposed Standard

is not a recommendation or endorsement by the U.S. Government and does not imply that the

equipment, instruments, or materials are necessarily the best available for the purpose.

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1 Table of Contents

2

3 1. Introduction ..................................................................................................................... 2

4 2. Scope ................................................................................................................................. 2

5 3. Terms and Definitions..................................................................................................... 3

6 4. General Recommendations............................................................................................. 3

7 5. Appendix A: Change Log ............................................................................................... 5

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9 1. Introduction

10 1.1. This document has been developed with the objective of improving the quality and 

11 consistency of friction ridge examination practices.

12

13 1.2. For the purposes of this document, examinations include both latent print processing 

14 conducted in a laboratory setting and friction ridge comparisons. These examinations 

15 and their results should be within the examination’s limitations and/or the probative 

16 needs of the customer and provided to customers in a timely manner. In some cases, 

17 limiting or deferring certain examinations that do not provide additional value to the 

18 needs of the case provides more timely results to the customer and conserves the 

19 resources of the forensic service provider (FSP).

20

21 1.3. Limited examinations are exams that are not exhaustive; evidence may exist that has not 

22 been partially or fully processed and/or latent prints exist that have not been analyzed 

23 and/or compared. 

24

25 1.3.1. Limited examinations are not random sampling methods.

26

27 1.4. In some situations, limited examinations are advantageous to FSPs for any of the 

28 following reasons (not an all-inclusive list):

29 1.4.1. probative value of the evidence

30 1.4.2. crime type considerations (i.e. people versus property)

31 1.4.3. backlog reduction

32 1.4.4. increased case throughput

33 1.4.5. effective resource allocation and usage

34

35 1.5. If limited examinations are performed, they should be performed in a manner that 

36 has the lowest assessed risk on the evidence and case.

37

38 1.6. In this document, the following verbal forms are used: “shall” indicates a requirement, 

39 “should” indicates a recommendation; “may” indicates permission; and “can” indicates a 

40 possibility or capability. 

41

42 2. Scope

43 2.1. This document describes what limited examinations are and provides the best practice 

44 recommendations on how limited examinations should be conducted. It also describes 

45 what documentation is necessary if limited examinations are utilized by a forensic 

46 service provider.

47

48 2.2. This document does not address limiting the collection and preservation of evidence.

49
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50 3. Terms and Definitions

51 For the purposes of this document, the following terms and definitions apply.

52

53 3.1. Comparison (phase of the Examination methodology): The search for and detection of 

54 similarities and differences in the observed data between two potentially corresponding 

55 friction ridge impressions.

56

57 3.2. Customer: Client, authority, organization or person(s) requesting the forensic services.

58

59 3.3. Examination: The act or process of observing, searching, detecting, recording, 

60 prioritizing, collecting, analyzing, measuring, comparing, and/or interpreting.

61

62 3.4. Examiner (Friction Ridge)/Competent Friction Ridge Examiner: An individual who has 

63 successfully completed their FSP’s training program and has demonstrated to the FSP 

64 that they possess the knowledge, skills and abilities to perform the tasks required of their 

65 current position. An individual authorized to conduct friction ridge examinations for the 

66 FSP by observing and interpreting data, making decisions, forming conclusions and 

67 opinions, issuing reports and/or providing testimony.

68

69 3.5. Forensic Service Provider (FSP): A forensic science entity or forensic science 

70 practitioner providing forensic science services.

71

72 3.6. Friction Ridge Detail/Features: The combination of ridge flow, ridge characteristics, and 

73 ridge structure of friction ridge skin, as observed and reproduced in an impression. A 

74 large subset of the observed data used to compare and interpret similarity or dissimilarity 

75 between two impressions.

76

77 3.7. Minutia: The point where a friction ridge begins, terminates, or splits into two or more 

78 ridges. A subset of the friction ridge detail/features traditionally consisting of ridge 

79 endings, bifurcations, and dots/short ridges used to compare and interpret similarity and 

80 dissimilarity between two impressions.

81

82 3.8. Observed Data: Any demonstrable information observed within an impression that an 

83 examiner relies upon to reach a decision, conclusion or opinion. This has historically 

84 been expressed as “features” or “minutiae,” but the use of the broader term “observed 

85 data” is inclusive of other types of data that may be considered beyond minutiae, such as 

86 quality, scars, creases, edge shapes, pore structure, and other friction ridge features.

87

88 4. General Recommendations

89 4.1. Evidence Processing

90

91 4.1.1. The probative value of evidence should be assessed when deciding which 

92 evidence to process first (i.e. not processing items determined to be irrelevant to 
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93 the case, halting comparisons after multiple identifications have been made to the 

94 same individual, etc.).

95

96 4.1.2. Offense type may be considered when determining which cases to process first. 

97 Offenses that present a more egregious threat to public safety may be prioritized; 

98 however, consideration should be given when determining the extent to which any 

99 particular case may be examined.

100

101 4.1.3. When considering backlog mitigation strategies, selecting specific processing 

102 techniques with higher sensitivity instead of conducting full sequential processing 

103 may be necessary to improve efficiency and throughput. When selecting limited 

104 processing techniques, the FSP should consider the potential of a given technique 

105 for negating subsequent processing. At a minimum, any friction ridge detail of 

106 potential value that has been developed shall be photographed and/or retained and 

107 the integrity of the item shall be maintained for potential future examination. 

108 Backlog reduction may also include conducting limited processing of certain 

109 items (e.g. cartridge cases, locks, etc.) that have a low success rate.

110

111 4.1.4. FSP submission guidelines may include packaging recommendations that will 

112 maximize latent print processing results (i.e. separating drugs from the packaging 

113 prior to submission).

114

115 4.2. Friction Ridge Impression Comparisons

116

117 4.2.1. Examiners may compare and search friction ridge impressions on the most 

118 probative items where friction ridge detail is developed first and may stop when 

119 the investigative needs of the customer have been met (i.e. person(s) of interest 

120 is/are identified). Additional comparisons can be completed by the request of the 

121 customer.

122

123 4.2.2. Develop and retain all suitable friction ridge impressions; however, defer any 

124 remaining manual comparisons once each named person of interest has been 

125 identified on the surface or item(s).

126

127 4.2.3. Submit and search all AFIS quality friction ridge impressions first and report any 

128 conclusions made from the automated searches. Non-AFIS quality friction ridge 

129 impression comparisons may be completed upon an additional request from the 

130 customer.

131

132 4.2.4. Perform automated searches using auto-extracted minutiae first (e.g. an LFIS 

133 search) and if no identifications are made, perform a second search by using 

134 manually-encoded minutiae or ‘cleaning up’ the auto-extracted minutiae.

135

136 4.2.5. Limit the number of respondents reviewed from the automated system candidate 

137 response list or adjust the score that must be obtained in order to review the 

138 respondents.
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139

140 4.2.6. FSP policy may allow or require the restriction on which databases are searched 

141 to reduce the amount of time spent on each examination (e.g. only search a local 

142 database for specific types of crimes).

143

144 4.3. Necessary Documentation and Reporting

145

146 4.3.1. The FSP shall communicate with the relevant stakeholders and customers when 

147 performing limited examinations; both to determine if the examination is still 

148 required and to establish the extent or order of the examinations.

149

150 4.3.2. Any FSP that performs or plans to perform limited examinations shall notify any 

151 customers of that policy in advance. The extent of the examination shall be 

152 documented in the case file and reported to the customer. This documentation 

153 shall include any evidence that was not processed and/or any friction ridge 

154 impressions that were of value that were not compared.

155

156 4.3.3. Any limited examination approach should be conducted with respect to reducing 

157 the inhibition of future processing and/or comparisons. This would allow 

158 additional examinations at a later date. It is up to the FSP to weigh the costs 

159 versus benefits in deciding whether to implement a limited examination policy.

160

161 5. Appendix A: Change Log

Version Date Change

1.0 DD/MM/YYYY Original Issue

162