STRs

“I was 99 percent sure it was him,” says Laura Helig…But I had heard about this new technology, STRs…I knew they could give us results on really tiny samples (Weinberg 216).

This new form of analyzing DNA emerged in 1999 and was exactly what Helig needed to catch Helena Greenwood’s killer. Short Tandem Repeats could not only be used on small amounts of DNA but could also give specificity. This article goes into detail about STR testing. Essentially the labs like SERI that worked on Fredini’s DNA analyzed the 6-loci tandem repeats and they matched the DNA found under Helena’s fingernails, which had been stored in evidence since the attack, almost a decade earlier. STR analysis was able to use the small amount of very old DNA found under Helena’s fingernails and match it to Frediani’s DNA which was kept in a DOJ freezer because he was a sex offender. This was the beginning of databases like CODIS that emerged in 1998 to catch criminals even easier then with just STR.

STRs