Author Archives: Sarah Rackley Olson

SWGFAST Sufficiency Graph

The Scientific Working Group on Friction Ridge Analysis, Study and Technology (SWGFAST) has a sufficiency graph for fingerprint comparison that may be useful for attorneys to use when discussing fingerprint comparisons with experts.sufficiency-graph

The sufficiency graph reflects the interplay between quality and quantity of minutiae. Minutiae are small details that are used in comparing one print to another, such as ridge endings, bifurcations, and dots. These may also be called points of comparison or features of a print. This interplay between quality and quantity determines the level of complexity of a latent fingerprint. By using this graph, a fingerprint examiner should be able to explain her determination of whether a latent print could be individualized to a source.

In the graph above, the solid curve in the graph defines the lower limit of the sufficiency of friction ridge details below which, in area marked A, an individualization decision is not warranted. The dotted curve indicates the boundary between complex and non-complex prints. In area marked B in the graph, the examination is considered as complex and an individualization may be warranted. In area marked C, the examination is considered as non-complex and an individualization is warranted. See SWGFAST, Document #10, Standards for Examining Friction Ridge Impressions and Resulting Conclusions § 6.4.1.1 and § 6.4.1.5 (quotations omitted). Available here.

Additionally, the rarity of the features is factored into the examiner’s analysis and may adjust the position on the graph upward or downward on the graph between the zones.

An attorney could use this graph to discuss a comparison with a fingerprint examiner and arrive at a more concrete understanding of the level of complexity of the comparison. This graph was generated based on the collective experience of members of SWGFAST, not based on any scientific study. So, the curve is not intended to set a fixed requirement about number of points/minutiae, but it might be a starting point for a conversation. For example, if the print has 2 minutiae and low quality, the examiner would have some explaining to do about any individualization made to the source of the print. But, if the print is in a border area, then the examiner and the attorney could discuss why the examiner reached a certain conclusion or not.

Attorneys should read the entire SWGFAST Standards document for a better understanding of how examiners compare latent prints and make decisions about individualization. An understanding of the SWGFAST procedures and the procedures of the examiner’s own lab will improve communication between an attorney and an examiner and will help an attorney evaluate the forensic evidence in the case.

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NACDL Releases Primers on Surveillance

With a focus on Fourth Amendment concerns, the National Association of Criminal Defense Lawyers (NACDL) recently began a series of surveillance primers. The first primers in the series provide information on Automated License Plate Readers, Cell Phone Location Tracking, and Cell Site Simulators. NACDL will periodically release more primers on surveillance technologies. These documents are available to members and non-members here.

Each primer describes what the technology is designed to do, how it is used, and suggested defense strategies to identify and challenge the use of these technologies. The primers discuss law enforcement justifications for their use and provide lists of resources to aid in further research. These are a great starting point to further one’s understanding of these technologies, including determining if they were used in a case.

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Using the PCAST Report in the Courtroom

The President’s Council of Advisors on Science and Technology (PCAST) report on Forensic Science in Criminal Courts: Ensuring Scientific Validity of Feature-Comparison Methods was released on September 20, 2016. (Available for free download here.) The PCAST report gives an in-depth look at the current state of certain forensic science disciplines. It makes recommendations as to the use of forensic science evidence in court, improvements to be made in research and improvements to be made in forensic science in general. This report will be very useful in the courtroom, as it uses a framework to assess scientific validity that mirrors the NC Rule of Evidence 702, which governs the admissibility of expert testimony.

The report evaluates whether eight areas of forensic evidence are foundationally valid and validly applied, which are equivalent to prongs two and three of Rule 702 (whether the testimony is the product of reliable principles and methods (prong 2) and whether the witness has applied the principles and methods reliably to the facts of the case (prong 3)).

The summary for each discipline examined is as follows:

  • DNA analysis of single-source and simple-mixture samples: Foundationally valid, but examiners should undergo rigorous and relevant proficiency testing, should routinely disclose in reports and testimony whether he or she was exposed to any facts of the case that might have influenced the conclusion, and should disclose upon request all information about quality testing and issues in the lab.
  • DNA analysis of complex-mixture samples: Objective analysis based on probabilistic genotyping is new but promising; more research by independent scientists pertaining to accuracy in different scenarios is needed. Some methods may be valid for use in certain situations (e.g., an adequate sample with up to 3 sources and at least a 20% contribution of the smallest contributor).
  • Bite mark analysis: Bite mark analysis as used to identify a source of a bite mark or to establish whether an injury is due to a human bite mark is scientifically unreliable, and additional research in this area is not warranted as it is unlikely to be developed into a reliable and accurate methodology.
  • Latent print analysis: Has a foundationally valid subjective methodology, but the false-positive rate is substantial and likely to be higher than expected by many jurors. Conclusions need to be accompanied by accurate information about reliability and false positive rates. Several steps should be taken to further strengthen latent finger print analysis, including blinded proficiency testing incorporated into regular casework, limiting an examiner’s access to potentially biasing information and applying a “linear” analysis (examining and documenting features of the unknown sample before comparing them to a known sample). All of these factors should be considered when determining whether the techniques were validly applied in the case at hand.
  • Firearms analysis: PCAST concluded that the foundational validity of firearm analysis had not been established: only one study was found that examined accuracy and reliability (and that met the criteria for how such a study should be designed and conducted). The false positive rate was 1 in 66 examinations (upper 95th percentile confidence limit 1 in 46 cases). PCAST recommended additional studies using representative samples to establish accuracy and the creation of databases to establish prevalence of features.
  • Footwear analysis: Foundational validity has not been established, as no properly designed empirical studies to evaluate accuracy in associating a shoe print to a specific shoe have been conducted. Additional research should also include creation of databases to establish prevalence of features.

The PCAST report did not do a comprehensive evaluation of microscopic hair analysis, but did review the Department of Justice’s (DOJ) recently released proposed Uniform Language for Testimony and Reports, and its Supporting Documentation, for this discipline. PCAST noted that DOJ’s statement that “microscopic hair comparison has been demonstrated to be a valid and reliable scientific methodology” is not supported by the available studies. The report specifically noted an FBI study from 2002 comparing microscopic hair analysis to DNA analysis in 170 samples, in which a false positive rate of 11% was found.

The PCAST report also gives suggestions as to how to improve research in forensics fields. To this end, it calls upon the National Institute of Standards and Technologies to take on the task of determining if new and current fields are foundationally valid as defined by the document. It also recommends that more unaffiliated scientists be consulted by the Organization of Scientific Area Committees. The report calls for the creation of a Metrology Resource Committee which it suggests be made up of independent scientists. This committee would review the OSAC’s standards with an eye towards their reliability and validity.

Also included in the report are suggestions for improving the use of forensic evidence in court. The report calls on the U.S. Attorney General to direct attorneys appearing on behalf of the USDOJ to ensure expert testimony meets the standards for scientific validity (p. 140-141). Furthermore, it provides guidance to judges in determining the scientific validity as a foundation for expert testimony. The report suggests that judges review false positive rates, the method’s sensitivity, the sufficiency of validation studies, the appropriateness of proficiency testing, adequacy of procedures used and documentation and whether appropriate limits on reporting language were employed. It also recommends that best practices materials and training on scientific evidence be made available for judges (p. 145).

The PCAST report also recommends that for each field, the proponent of the forensic evidence

  • Demonstrate the capability of the analyst through routine, blinded proficiency testing.
  • Demonstrate that the techniques were reliably applied in the case by providing a complete description of the procedures, results and laboratory notes.
  • Utilize comprehensive and accurate reporting and testimony, including information from the empirical studies of false positive rates and sensitivity, information on the comparability between the types of samples used in these empirical studies and the sample(s) available in the particular case, and an accurate portrayal of the probative value of the observed features (i.e., how common or rare the features are, based on empirical studies).

This report will be useful for attorneys considering a challenge to testimony by forensic experts, as it explains in an accessible way what must be shown to demonstrate reliable principles and methods and reliable application of those principles and methods in a particular case. It is a worthwhile read for every criminal advocate as it suggests a framework for making a rigorous challenge to the admissibility of expert testimony.

The National Association for Public Defense is offering a webinar entitled, Denuding the Emperor: Understanding and Using the PCAST Forensic Science Report at 1:00 pm on Dec. 2, 2016.  Andrew Northrup, Assistant Public Defender in the Maryland Office of the Public Defender will discuss how the PCAST report can be used in the courtroom. The program is free of charge for NAPD members and $20 for non-members.

I would like to thank Glinda Cooper, Director of Science and Research for the Innocence Project for her contribution to this post.

 

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Center for Nursing Excellence International Releases Multidisciplinary Sexual Assault Glossary

It can be frustrating when a term means something to one discipline yet has a different definition when used in another discipline. Thus, together with the Forensic Technology Center of Excellence (FTCoE), the Center for Nursing Excellence International (CFNEI) has released a glossary of terms used in sexual assault cases.  The Multidiscipline Sexual Assault Glossary is a continuously updated searchable database compiled with the input of experts in several fields.

With this glossary, attorneys can ensure clear communication with jurors as well as experts consulted in the course of sexual assault cases.  As the definitions are FBI-compliant, one can be confident in their veracity and clarity.  The glossary will be available as a smartphone app in the future.

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Crime Laboratory Essentials Webinar

Take a tour inside a state-operated crime lab with Professor Carol Henderson, Director of Stetson’s National Clearinghouse for Science, Technology, and the Law (NCSTL); Ann Talbot, the director of the Metro Nashville, Police Department Crime Laboratory; and Christine Funk, a criminal defense attorney with over 20 years of practice experience.

Crime Laboratory Essentials is a webinar provided by the Capital Litigation Initiative: Crime Scene to Courtroom Forensics Training series funded by the US Department of Justice. This seminar follows all the steps of forensic analysis for the five core disciplines of Forensic Science: latent fingerprint analysis, firearms, forensic biology (DNA analysis), drug identification, and toxicology. The free archived version of the webinar is available via the link above.

Using evidence from a mock crime to show the lab procedures and machinery used, this webinar takes you step by step through how each of these five sorts of evidence is tested. The panelists also provide additional information about each of the techniques by responding to questions from the audience. If you have a question about how a lab operates, from chain of custody, to testing, to post-trial evidence storage, this webinar has answers.

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New Research on “Touch” DNA

As the sensitivity of DNA analysis increases, scientists are able to develop profiles from ever-smaller samples of DNA. This has lead to testing of a wider array of samples collected from crime scenes, including window panes, bullets, hats and other clothing, cigarette butts, and many other items.

Attorneys sometimes ask me about the likelihood of obtaining a useful DNA profile from certain items of evidence. A study from six European forensic laboratories may give some idea of how likely it is to find a DNA profile on items commonly found at crime scenes. This article contains an interesting chart that lists the item and the likelihood of finding a full profile, usable partial profile, possibly usable partial profile, or no profile. It seems best to use this type of information as a rough guide, but it is interesting nonetheless.

It is important to keep in mind that as labs are able to analyze smaller amounts of DNA, the possibility of developing partial profiles and complex DNA mixtures increases. Where very small amounts of DNA are involved, the sample may have been deposited by secondary transfer. Here’s an interesting article on secondary transfer and “touch” DNA.

Attorneys should be aware that forensic laboratories may have case submission guidelines that limit the number and type of items that may be tested by the lab. To understand why and how an item was tested (or not), it is important to read the lab’s policies and guidelines. Here is a link to the North Carolina State Crime Lab’s Evidence Guide. There is information about Touch DNA testing on p. 52.

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Reliability Concerns Regarding Probation Drug Screens

The NC Department of Public Safety (DPS) has begun relying on less accurate presumptive testing for urine screens for drugs for probation, prison, and DSS cases. The focus of this post will be probation cases, though the testing is the same for prison and DSS cases.

Testing Prior to 2014

Until February 2014, the Department of Public Safety maintained two laboratories with trained staff and EMIT analyzers (an immunoassay test) to run either initial testing or additional testing on urine that gave a positive result on an screening test. These labs tested approximately 125,000 samples per year. The North Carolina State Crime Lab uses similar equipment to the former DPS labs for presumptive toxicology testing.

Current Drug Testing Procedures

The DPS labs were closed in early 2014. On-site urine drug screening is now performed by probation officers using a presumptive test kit similar to the type of urine dip test that can be purchased over the counter at many stores. Currently, additional testing is completed by Norchem, a private lab in Arizona, only when the test subject immediately denies use of a controlled substance. If the test subject admits use, the urine specimen is discarded and a positive result is reported (See NC DPS Division of Adult Correction and Juvenile Justice – Community Corrections – Policy & Procedures – Chapter H – Section .0400 Substance Abuse Screening Program, available at https://www.ncdps.gov/div/CC/Publications/Policy.pdf, p. 367, subsection (i)). Because the urine sample is discarded, if the test subject later denies use, the sample cannot be re-tested using more reliable methods.

Reditest and the Need for Confirmatory Testing

The Reditest Panel Dip Test (“Reditest”) is the on-site screening test currently used by probation officers. The Reditest is one of many presumptive test kits which are intended to screen for drugs in urine. The Reditest package insert which describes how to use the product states in its “Limitations” section that the test “provides only a preliminary analytical test result. A secondary analytical method must be used to obtain a confirmed result.” The instruction card for a similar product can be found here. The instructions note that gas chromatography/mass spectrometry (GC/MS) is the “preferred confirmatory method.”

Reditest and Lack of Validation and On-Site Quality Assurance and Quality Control

Reditest recommends but does not provide “positive and negative controls to be tested as good laboratory practice to confirm the test procedure and to verify proper test performance.” Reditest kits are not being validated by the end user in North Carolina. If batches of test kits are not validated, there is no check on the accuracy of kits being used in the state. Immunoassay testing performed by the DPS labs prior to 2014 revealed that on several occasions the on-site test kits shipped to probation and other offices did not work as expected and yielded either inaccurate or uninterpretable results.

To administer the Reditest, a provider dips a portion of the card in a urine sample for 15 seconds. Five minutes later the results can be obtained. The card should have a control line appear in each testing area. If any line appears in the testing section (no matter how faint), the results are negative for that screen. If a line does not appear in the testing section, the manufacturer’s website explains how to send the sample to a laboratory for confirmatory testing. Administration of these presumptive tests by probation officers instead of individuals with scientific training further complicates the potential for incorrect results.

False Positives with Reditest

Included on the package insert are a subset of clinical studies which demonstrate the preliminary nature of the test. Agreement with GCMS, a more accurate confirmatory test, ranged from 89%-99%. The numbers demonstrate the possibility for false positives. In tests such as these, a false positive is typically caused by a legal substance which the kit confuses with an illicit drug. Most commonly this involves over-the-counter medications. For example, some kits will register pseudoephedrine as methamphetamine. The FDA also notes that results from these types of tests can be affected by how the test was performed, how the urine was stored, what the person ate or drank before taking the test, and any other medications the person may have taken.

Admissibility of Screening Test Results

In State v. Carter, 765 S.E.2d 56 (N.C. App. 2014), the N.C. Court of Appeals held that field drug test kits, which are presumptive tests, are inadmissible due to their lack of reliability. The Court noted that for testing of controlled substances to be admissible, it “must be based on a scientifically valid chemical analysis[.]” To establish that a test is admissible, the party must present evidence that the test methods are sufficiently reliable. Results of these initial tests without confirmatory testing should not be admissible and should not be sufficient for the basis of revocation of probation.

Screening Tests and Workplace Testing

Use of the Reditest would not meet federal guidelines for workplace testing. The U.S. Department of Health and Human Services (HHS) 2015 Mandatory Guidelines for Federal Workplace Drug Testing requires that an initial drug test be an immunoassay or alternate technology, such as spectrometry or spectroscopy. (Section 11.9, Available at https://www.federalregister.gov/articles/2015/05/15/2015-11523/mandatory-guidelines-for-federal-workplace-drug-testing-programs#p-426) An HHS-certified laboratory must validate an initial drug test before testing specimens. (Section 11.9) Initial test results must be confirmed by an analytical method that uses mass spectrometric identification. Such methods include gas chromatography/mass spectrometry (GC/MS), liquid chromatography/mass spectrometry (LC/MS), GC/MS/MS, LC/MS/MS] or equivalent. (Section 11.12) Only specimens that yield a positive result on initial and confirmatory tests are reported as positive results. (Section 11.17)

In North Carolina, the testing used to allege a probation violation, revoke probation or remove a child from a parent’s custody would not qualify as even an initial test in the federal employment context.

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