PHOENIX (KSAZ) - When authorities announced the arrest of Ian Mitcham in connection with the 2015 murder of Allison Feldman Tuesday, they said detectives used a new technique called "Familial DNA" to help them crack the case.
So what is Familial DNA?
Familial DNA allows investigators to search a wider parameter of the DNA sample, in hopes of identifying those who are "likely" related to the suspect.
In the case of Feldman, authorities got a hit from Mitcham's brother's DNA. DNA collected from Feldman's home was in the hands of detectives for years, and sent through hundreds of databases each day, looking for a match.
The method was reportedly pioneered over a decade ago in Great Britain, and has been used to solve a number of high-profile cold cases in recent years.
According to a 2016 article by the Los Angeles Times, Familial DNA played a role in the arrest of a person, in connection with the "Grim Sleeper" murders.
Only 12 states have used the method. In Arizona, the case must meet three requirements: the case must be a cold case, an extremely violent crime, and investigators must have exhausted all leads and means. Only then can a department make a request to DPS for familial DNA testing.
Some, however, have raised ethical and privacy concerns with Familial DNA.
"Because some civil liberties groups claims that it violates the constitutional rights of people, because you're investigating people ie. relatives who have not committed any crimes, just based on the fact that they're related to a guy who's in question," said legal expert Brian Foster.
Some also question the cost and validity.