A forensic expert who was retained by Bryan Kohberger's defense team said his lawyers should testify in his push to walk back his guilty plea. Kohberger pleaded guilty last year to murdering four University of Idaho students, and he is serving four life sentences in an Idaho prison. An FBI lab, according to defense expert Brent Turvey, determined the hairs weren't from Kohberger. While it suggests there were other people involved, it doesn't prove Kohberger wasn't, Gray said. She also said the defense had long been aware of the evidence.