MOSCOW, Idaho (NewsNation) — Monday marked one year since four University of Idaho students were killed at an off-campus home in the small town of Moscow.

Bryan Kohberger, 28, faces charges in the stabbing deaths of Kaylee Goncalves, 22; Madison Mogen, 21; Xana Kernodle, 20, and Ethan Chapin, 20. The four were found dead inside an off-campus rental home in the early morning hours of Nov. 13, 2022.

A vigil was hosted by university students Monday evening to remember the lives of the four students. University of Idaho alumni across the nation were encouraged to turn their porch lights on from 6 p.m. to 7 p.m. PST in solidarity.

Kohberger was arrested more than a month later at his parents’ home in Pennsylvania. He was extradited to Idaho and is facing four counts of murder.

At the time of the killings, Kohberger was a graduate student in criminology at Washington State University, located just a few miles from Moscow.

Prosecutors identified Kohberger as a suspect using genetic genealogy, a process that takes DNA evidence and compares it to genetic information from family members that may be found on genealogy sites like Ancestry.com or 23andMe. Investigators use DNA to identify possible family connections which, combined with other evidence like the white Hyundai Elantra seen near the scene, can help narrow down a suspect.

However, the DNA evidence could be greatly important for Kohberger’s defense because there are privacy concerns with the information due to the names and genetic information of individuals totally unrelated to the case that could be included in family trees in the reports.

The judge overseeing the trial set a Dec. 1 deadline for prosecutors to turn over DNA evidence critical to the case, saying he preferred to review all of the evidence at one time. He did note a potential for future delays if the Department of Justice has not produced the requested reports by the deadline.

With Kohberger’s trial set to take place next year, his court appearances have been tough for the Goncalves family. But Kaylee’s father, Steve, previously said the family would “be there at every moment” of the legal process.

Kohberger faces four charges of first-degree murder and one charge of burglary. He entered a not guilty plea in May. If convicted, he could face the death penalty.