A nonparametric Bayesian approach to the rare type match problem

The "rare type match problem" is the situation in which the suspect's DNA profile, matching the DNA profile of the crime stain, is not in the database of reference. The evaluation of this match in the light of the two competing hypotheses (the crime stain has been left by the suspect or by another person) is based on the calculation of the likelihood ratio and depends on the population proportions of the DNA profiles, that are unknown. We propose a Bayesian nonparametric method that uses a two-parameter Poisson Dirichlet distribution as a prior over the ranked population proportions, and discards the information about the names of the different DNA profiles. This fits very well the data coming from European Y-STR DNA profiles, and the calculation of the likelihood ratio becomes quite simple thanks to a justified Empirical Bayes approach.Comment: arXiv admin note: text overlap with arXiv:1506.0844

DNA-Based Kinship Analysis

Relatedness between individuals and groups can be investigated using DNA markers. A child’s DNA profile is a combination of alleles passed down from the father and mother. This means that relationships can be investigated between alleged family members. DNA profiling is commonly used to test for potential paternity, parentage and sibship (whether people are related as brothers or sisters) relationships. In many forensic cases more complex relationships have to be considered

The Similarity Measurement of Human DNA Profile Using Fuzzy Similarity

This research investigated the similarity of human DNA profile using fuzzy similarity measure. The similarity measurement of DNA profile had been done by measuring the similarity between query’s DNA profile and its biological family such as father, mother, brother, sister, grandmother and grandfather. The similarity measurement had been done to the short tandem repeat (STR) alleles in sixteen loci. The result of the experiment showed that each simulation gave matching result. This research is useful for Indonesian National Police (POLRI) in identifying process of disaster victim, terrorism victim and other criminal conduct

Optical Tweezers as an Effective Tool for Spermatozoa Isolation from Mixed Forensic Samples

A single focus optical tweezer is formed when a laser beam is launched through a high numerical aperture immersion objective. This objective focuses the beam down to a diffraction-limited spot, which creates an optical trap where cells suspended in aqueous solutions can be held fixed. Spermatozoa, an often probative cell type in forensic investigations, can be captured inside this optical trap and dragged one by one across millimeter-length distances in order to create a cluster of cells which can be subsequently drawn up into a capillary for collection. Sperm cells are then ejected onto a sterile cover slip, counted, and transferred to a tube for DNA analysis workflow. The objective of this research was to optimize sperm cell collection for maximum DNA yield, and to determine the number of trapped sperm cells necessary to produce a full STR profile. A varying number of sperm cells from both a single-source semen sample and a mock sexual assault sample were isolated utilizing optical tweezers and processed using conventional STR analysis methods. Results demonstrated that approximately 50 trapped spermatozoa were required to obtain a consistently full DNA profile. A complete, single-source DNA profile was also achieved by isolating sperm cells via optical trapping from a mixture of sperm and vaginal epithelial cells. Based on these results, optical tweezers are a viable option for forensic applications such as separation of mixed populations of cells in forensic evidence

Plaintiff\u27s Exhibit 0276: Sheppard DNA Profile

https://engagedscholarship.csuohio.edu/plaintiff_exhibits_2000/1044/thumbnail.jp

En god og en dårlig nyhet: Om DNAs effekt på oppklaringsprosenten i vinningssaker

Nordisk politiforskning er et Open Access-tidsskrift. Hele tidsskriftet er tilgjengelig på Idunn: https://www.idunn.no/nordisk_politiforskning/2016/01The expansion of the Norwegian DNA database in 2008, the so called «DNA reform», was founded on the belief that DNA increases the detection rate of volume crime significantly. We have conducted a study of Norwegian police registers to see what effects DNA actually has on detection rates in volume crime. The good news is that there is little doubt that DNA affects the detection rate. The overall detection rate for the criminal offenses we have studied in our selected police districts in the selected period was 8 %. In cases with a DNA profile the detection rate was 44 %. In cases with hits against the DNA identity register the detection rate was 81%, and in cases with hits against the DNA investigation register the detection rate was 62 %. However, the bad news is the very low proportion of cases where police gather biological samples which result in a DNA-profile and hits. This implies that no matter how high the detection rate is in cases with DNA profile, it will not affect the overall detection rate

En god og en dårlig nyhet: Om DNAs effekt på oppklaringsprosenten i vinningssaker

Nordisk politiforskning er et Open Access-tidsskrift. Hele tidsskriftet er tilgjengelig på Idunn: https://www.idunn.no/nordisk_politiforskning/2016/01The expansion of the Norwegian DNA database in 2008, the so called «DNA reform», was founded on the belief that DNA increases the detection rate of volume crime significantly. We have conducted a study of Norwegian police registers to see what effects DNA actually has on detection rates in volume crime. The good news is that there is little doubt that DNA affects the detection rate. The overall detection rate for the criminal offenses we have studied in our selected police districts in the selected period was 8 %. In cases with a DNA profile the detection rate was 44 %. In cases with hits against the DNA identity register the detection rate was 81%, and in cases with hits against the DNA investigation register the detection rate was 62 %. However, the bad news is the very low proportion of cases where police gather biological samples which result in a DNA-profile and hits. This implies that no matter how high the detection rate is in cases with DNA profile, it will not affect the overall detection rate

Is there a relationship between fingerprint donation and DNA shedding?

This research investigates the possible relationship between fingerprint donation and DNA shedding. Volunteers were asked to provide a series of fingerprint depletions on glass. The level of fingerprint detail developed and DNA profiling results obtained were compared for each donor to investigate whether a relationship between fingerprint donation and DNA shedding exists. Our results suggest that between comparisons of donors, there is no statistical difference between the left and right hand of our volunteers in terms of fingerprint donation, but there is a statistical difference in terms of DNA shedding with three of our eight donors. Our results also indicate that there is no correlation between fingerprint donation and DNA shedding, meaning that an enhanced fingerprint with full ridge detail will not necessarily give a full DNA profile. In serious crime, these two avenues of evidence must be explored