Attorneys for a man charged with murder in connection with the killings of four University of Idaho students are asking a judge to throw out most of the evidence in the case because they say it all hinges on an unconstitutional genetic investigation process.

Bryan Kohberger is charged with four counts of murder in the deaths of Ethan Chapin, Xana Kernodle, Madison Mogen and Kaylee Goncalves.

Criminal defense attorney Joshua Ritter says Idaho college killings suspect Bryan Kohberger’s defense has a “slim” chance of dismissing DNA evidence, which is crucial to the prosecution’s case. Without an explanation for how Kohberger’s DNA ended up on a knife sheath found at the crime scene or a way to exclude the evidence,