Searching for first-degree familial relationships in California's offender DNA database: Validation of a likelihood ratio-based approach

Myers, Steven; Timken, Mark D.; Piucci, Matthew L.; Sims, Gary A.; Greenwald, Michael A.; Weigand, James J.; Konzak, Kenneth C.; Buoncristiani, Martin R.

doi:10.1016/j.fsigen.2010.10.010

Cited by 40 publications

(60 citation statements)

References 13 publications

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“…One possible correction would be increasing the value of the parameter , however, in Figure S6 we see that even when the true allele frequencies are assumed, increasing decreases distinguishability. If more genetic data were used, particularly markers on the Y chromosome or mitochondrial DNA, as are in some states but not Federally, profile informativeness could be increased to the point where allele frequency approximations made little difference in the ultimate outcome (Figure S5) [10], [52]. However, additional Y chromosome and mitochondrial markers will only inform matrilinial or patrilinial relationships and any additional markers will be subject to similar population-specific variation, and will be limited by practical genotyping constraints and the need to avoid medically-associated regions.…”

Section: Discussionmentioning

confidence: 99%

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Familial Identification: Population Structure and Relationship Distinguishability

2012

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With the expansion of offender/arrestee DNA profile databases, genetic forensic identification has become commonplace in the United States criminal justice system. Implementation of familial searching has been proposed to extend forensic identification to family members of individuals with profiles in offender/arrestee DNA databases. In familial searching, a partial genetic profile match between a database entrant and a crime scene sample is used to implicate genetic relatives of the database entrant as potential sources of the crime scene sample. In addition to concerns regarding civil liberties, familial searching poses unanswered statistical questions. In this study, we define confidence intervals on estimated likelihood ratios for familial identification. Using these confidence intervals, we consider familial searching in a structured population. We show that relatives and unrelated individuals from population samples with lower gene diversity over the loci considered are less distinguishable. We also consider cases where the most appropriate population sample for individuals considered is unknown. We find that as a less appropriate population sample, and thus allele frequency distribution, is assumed, relatives and unrelated individuals become more difficult to distinguish. In addition, we show that relationship distinguishability increases with the number of markers considered, but decreases for more distant genetic familial relationships. All of these results indicate that caution is warranted in the application of familial searching in structured populations, such as in the United States.

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Section: Discussionmentioning

confidence: 99%

“…Its use in the United States has been more limited due to concerns regarding civil liberty infringement, racial bias, and efficacy [3]–[6]. However, in July 2010, familial searching was used in a highly publicized California case to identify a suspect serial killer (the “Grim Sleeper”) [7]–[10].…”

Section: Introductionmentioning

confidence: 99%

Familial Identification: Population Structure and Relationship Distinguishability

2012

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“…However, no validation data were provided to evaluate the effectiveness of the recommendation. California implemented this recommendation for three populations instead of four (i.e., southeastern Hispanics was excluded) and evaluated the false negative and false positive rates for 100 test families in a database with 1 million profiles [10]. A more comprehensive study with a larger number of pedigrees and various sizes of databases, such as from small local databases (∼10,000) to national databases (∼10 million), would have provided more insight on the performance (in terms of false positive and false negative rates) of recommendation 6.…”

Section: Introductionmentioning

confidence: 99%

Kinship Index Variations among Populations and Thresholds for Familial Searching

Budowle²

2012

PLoS ONE

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Current familial searching strategies are developed primarily based on autosomal STR loci, since most of the offender profiles in the forensic DNA databases do not contain Y-STR or mitochondrial DNA data. There are generally two familial searching methods, Identity-by-State (IBS) based methods or kinship index (KI) based methods. The KI based method is an analytically superior method because the allele frequency information is considered as opposed to solely allele counting. However, multiple KIs should be calculated if the unknown forensic profile may be attributed to multiple possible relevant populations. An important practical issue is the KI threshold to select for limiting the list of candidates from a search. There are generally three strategies of setting the KI threshold for familial searching: (1) SWGDAM recommendation 6; (2) minimum KI≥KI threshold; and (3) maximum KI≥KI threshold. These strategies were evaluated and compared by using both simulation data and empirical data. The minimum KI will tend to be closer to the KI appropriate for the population of which the forensic profile belongs. The minimum KI≥KI threshold performs better than the maximum KI≥KI threshold. The SWGDAM strategy may be too stringent for familial searching with large databases (e.g., 1 million or more profiles), because its KI thresholds depend on the database size and the KI thresholds of large databases have a higher probability to exclude true relatives than smaller databases. Minimum KI≥KI threshold strategy is a better option, as it provides the flexibility to adjust the KI threshold according to a pre-determined number of candidates or false positive/negative rates. Joint use of both IBS and KI does not significantly reduce the chance of including true relatives in a candidate list, but does provide a higher efficiency of familial searching.

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“…False positives when the Q profile has common alleles that are shared by unrelated people can result in long candidate lists. Y-STR testing on male samples from a ranked candidate list can help filter false positives [48]. While familial searching is unlikely to be conducted on a national level in the USA [49], it has produced some successes in the UK through aiding identification of 41 perpetrators in 188 police investigations [50].…”

Section: (C) Stronger Conclusion With Challenging Samplesmentioning

confidence: 99%

The future of forensic DNA analysis

Butler

2015

Phil. Trans. R. Soc. B

172

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One contribution of 15 to a discussion meeting issue 'The paradigm shift for UK forensic science'. The author's thoughts and opinions on where the field of forensic DNA testing is headed for the next decade are provided in the context of where the field has come over the past 30 years. Similar to the Olympic motto of 'faster, higher, stronger', forensic DNA protocols can be expected to become more rapid and sensitive and provide stronger investigative potential. New short tandem repeat (STR) loci have expanded the core set of genetic markers used for human identification in Europe and the USA. Rapid DNA testing is on the verge of enabling new applications. Next-generation sequencing has the potential to provide greater depth of coverage for information on STR alleles. Familial DNA searching has expanded capabilities of DNA databases in parts of the world where it is allowed. Challenges and opportunities that will impact the future of forensic DNA are explored including the need for education and training to improve interpretation of complex DNA profiles.

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Searching for first-degree familial relationships in California's offender DNA database: Validation of a likelihood ratio-based approach

Cited by 40 publications

References 13 publications

Familial Identification: Population Structure and Relationship Distinguishability

Familial Identification: Population Structure and Relationship Distinguishability

Kinship Index Variations among Populations and Thresholds for Familial Searching

The future of forensic DNA analysis

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