Highlights
- •We investigate whether mixtures have a donor in common using a likelihood ratio approach.
- •This is a generalization of traditional trace-person likelihood ratios to trace-trace LR's.
- •We describe the implementation of the method for a semi-continuous evaluation model.
- •We investigate the method's efficiency using our semi-continuous model for various mixture types.
- •We describe in detail the application of the method to the mixtures in the Dutch DNA database.
Abstract
Several methods exist to compute the likelihood ratio LR(M, g) evaluating the possible contribution of a person of interest with genotype g to a mixed trace M. In this paper we generalize this LR to a likelihood ratio LR(M1, M2) involving two possibly mixed traces M1 and M2, where the question is whether there is a donor in common to both traces. In case
one of the traces is in fact a single genotype, then this likelihood ratio reduces
to the usual LR(M, g). We explain how our method conceptually is a logical consequence of the fact that
LR calculations of the form LR(M, g) can be equivalently regarded as a probabilistic deconvolution of the mixture.
Based on simulated data, and using a semi-continuous mixture evaluation model, we
derive ROC curves of our method applied to various types of mixtures. From these data
we conclude that searches for a common donor are often feasible in the sense that
a very small false positive rate can be combined with a high probability to detect
a common donor if there is one. We also show how database searches comparing all traces
to each other can be carried out efficiently, as illustrated by the application of
the method to the mixed traces in the Dutch DNA database.
Keywords
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Article info
Publication history
Published online: October 13, 2016
Accepted:
October 1,
2016
Received in revised form:
August 13,
2016
Received:
March 11,
2016
Identification
Copyright
© 2016 Elsevier Ireland Ltd. All rights reserved.
