North Louisiana Crime Lab adopts STRmix DNA software

The North Louisiana Crime Laboratory has begun using STRmix probabilistic genotyping software, becoming the 99th U.S. forensic lab on the platform. The move expands the lab’s ability to interpret complex DNA mixtures in violent crime, sexual assault and cold-case investigations.

Why it matters: - STRmix gives forensic labs a way to interpret mixed or degraded DNA profiles that were previously too complex to analyze with older methods. - The software can turn more crime scene evidence into usable results in cases where DNA once came back inconclusive. - The North Louisiana Crime Laboratory’s adoption expands access to the software in a region serving 29 parishes.

What happened: - The North Louisiana Crime Laboratory joined 98 other U.S. forensic laboratories using STRmix probabilistic genotyping software. - The lab said it is the first in the United States to validate the VeriFiler™ Plus PCR amplification kit with STRmix. - Jessica Esparza, Ph.D., the lab’s DNA Technical Leader, said the validation lets NLCL use more information in a DNA profile to deconvolute complex mixtures.

The details: - STRmix has been used since 2012 and has produced usable, interpretable and admissible DNA results in more than 700,000 criminal cases worldwide. - The software has been especially effective in violent crime, sexual assault and cold-case investigations. - NLCL serves the northern 29 parishes in Louisiana and provides forensic services from laboratories in Shreveport and Alexandria, plus an evidence hub in Ouachita. - NLCL’s services include drug chemistry, DNA analysis, firearms examination, fire debris analysis and forensic toxicology. - STRmix uses a fully continuous model rather than fixed stochastic thresholds and other manual biological parameters. - The software proposes hundreds of thousands of possible profiles, weighs how closely they match the observed DNA mixture and assigns a likelihood ratio when a person of interest’s sample is available. - More than 120 forensic laboratories worldwide use STRmix, including labs in the U.S., Canada, the U.K., Europe, Asia, the Middle East, the Caribbean, New Zealand and Australia. - All nine state and territory forensic labs in New Zealand and Australia use the software. - The STRmix product family also includes DBLR™, FaSTR™ DNA and STRmix™ NGS. - DBLR enables kinship analysis, database searches, visualization of DNA mixture evidence and mixture-to-mixture matching when used with STRmix. - FaSTR DNA analyzes raw DNA data and estimates the number of contributors. - STRmix NGS interprets profiles generated using next-generation sequencing. - A more information link is available for STRmix.

Between the lines: - The validation of a new PCR amplification kit with STRmix suggests the lab can extract more value from challenging samples. - The adoption also reflects broader reliance on probabilistic genotyping as forensic labs push to recover evidence that older binary methods could not resolve. - The company’s broader suite points to an end-to-end workflow, from raw data analysis to interpretation and database matching.

What's next: - NLCL will use STRmix in ongoing forensic casework across northern Louisiana. - The software’s wider adoption suggests more labs may continue moving toward continuous-model DNA interpretation for complex evidence. - STRmix NGS may further expand the types of DNA profiles laboratories can analyze.