A private lab in Texas will perform DNA tests on old biological material from a 1980s Minneapolis serial killer case, a Hennepin County judge ruled Wednesday.

The Minnesota Innocence Project, which is seeking to exonerate 71-year-old Billy Glaze for the murders of three American Indian women, sought to have the testing done at Cellmark Forensics in Dallas. That lab tested other material samples in the case and found previously undiscovered, intact sperm on evidence taken from one of the victim’s bodies.

Prosecutors, who maintain that they have the right man behind bars for the killings, argued it is better practice to have a public lab do the testing. They sought to send the evidence to the Minnesota BCA crime lab.

The sperm evidence is important because its intact condition means it was likely deposited right before the victim was killed, defense attorneys said.

They argue there is no biological evidence linking Glaze to the serial murders, including in DNA tests performed in recent years on 39 pieces of evidence from the murder scenes. Instead, they argue, two pieces of evidence link the murders to another man — a convicted rapist whom they declined to identify publicly.

Judge Toddrick Barnette ruled that the sperm evidence should be tested in Texas and ordered that a state expert be sent to observe the testing process. The defense has offered to pay expenses for the state expert’s trip.