The FBI has now gotten involved in the case regarding four University of Idaho students who were found deceased this week, according to Fox News.

On Sunday at noon, Ethan Chapin, Kaylee Goncalves, Xana Kernodle and Madison Mogen were found dead inside their Moscow, Idaho, residence. The four were University of Idaho students. The police have not yet apprehended a suspect. Per the Deseret News, investigators believe that an edged blade was used during the suspected homicide.

According to the Deseret News, authorities responded to a 911 call reporting an unconscious body on Sunday. When officers went to investigate, they found the bodies of the four students. CBS News reported that Moscow Mayor Art Bettge said the students likely died hours before noon, somewhere between 3 a.m. and 4 a.m.

On Thursday, the Latah County Coroner released the autopsy results. The coroner listed the cause of death as “homicide — murder.”

CNN reported that Jeffrey Kernodle, the father of victim Xana Kernodle, cited the autopsy results and said that she had fought back. “Bruises, torn by the knife. She’s a tough kid,” Kernodle said.

According to ABC News, two other roommates were home at the time when the four students were believed to be killed. ABC News reported, “Thompson said it’s unusual to not have a suspect or motive at this point, and noted that this case has brought in more resources and manpower to Moscow than he’s ever seen in his 30 years as prosecutor.”

On Wednesday, police chief James Fry backtracked on a previous statement that there was no imminent threat to the community, according to CNN. Fry said that those who live in the area should “stay vigilant.”