Police markets are seen at a crime scene after an explosion in Zagreb, Croatia, Jan. 23, 2013. Reuters

Authorities in New York have turned to a controversial DNA technique as a last resort in identifying the killer of Karina Vetrano, a 30-year-old jogger who was murdered while running in Queens in August. A DNA sample was retrieved from Vetrano’s body when she was found but did not produce a match in either state or local databases.

Queens District Attorney Richard Brown asked the State Commission on Forensic Science Thursday to authorize the use of a DNA technique called familial searching which uses obtained DNA to identify a criminal’s relatives.

“This tragic murder has been exhaustively investigated using every tool currently available,” said Brown.

New York State officials will review the request before making a decision about the case, but the world of familial DNA searching is considered murky territory. Arguments against the procedure say that involving innocent family members is unfair.

“Familial searches are suspicionless, generalized and arbitrary,” wrote Erin E. Murphy, a member of the American Bar Association in a paper entitled “Familial DNA Searches: The Opposing Viewpoint.” California, Texas, Florida and seven other states allow familial DNA tests while Maryland and the District of Columbia have prohibited it.

“A policy that implicates New Yorkers in a criminal investigation solely because they are related to someone with DNA in the state’s database is a miscarriage of justice,” said New York Civil Liberties Union Executive Director Donna Lieberman.

A petition addressed to the Department of Justice on Change.org asking for the allowance of DNA testing to find Vetrano's killer garnered more than 9,000 signatures.

Familial DNA testing could be the last resort for prosecutors in the case, which entered its fourth month of investigation in December. Vetrano was running in a section of Spring Creek Park in Howard Beach, New York known as “the weeds” Aug. 2 when she was sexually assaulted and murdered. Her father and police found her body 15 feet off the running trail later that day.

“Our only goal in life is to find out who did this to our daughter,” said her mother, Cathy Vetrano. “So if there’s any available method to do that, we want it done.”