BOISE, Idaho (AP) — Idaho police pieced together DNA evidence, cellphone data and surveillance video to charge a criminology graduate student with the November slaying of four University of Idaho undergraduates, according to an affidavit unsealed Thursday.

The affidavit says DNA matching that of 28-year-old Bryan Kohberger was found on a knife sheath recovered at the crime scene, just a short drive across the state border where he is a doctoral student at Washington State University.

The affidavit also says that a cellphone belonging to Kohberger was near the victims' home on a dozen occasions...