A knife sheath with DNA on it that was found at the apartment house where four University of Idaho students were stabbed to death in 2022 could have been planted by the actual killer, defense lawyers for suspect Bryan Kohberger may argue at his trial.

In the case against Bryan Kohberger, the man accused of killing four University of Idaho students in November 2022, the prosecution’s most important piece of evidence is a DNA sample taken from a knife sheath left at the crime scene.