(NewsNation) — The residence where four University of Idaho students were found brutally stabbed to death was set to undergo a professional cleaning on Friday morning, police said.

Former CIA officer and FBI special agent Tracy Walder said on “Morning in America” that this probably means police are done gathering whatever evidence they think is there.

“It sounds to me like the police are completely done processing this crime scene,” Walder said.

In a video on social media, Moscow Police Chief James Fry said part of the reason they are cleaning the house is because of the biohazards and chemicals used during the investigations.

There is no timeline for the completion of the cleaning, police said. When it is finished, the residence will be returned to its property management company.

University of Idaho students Kaylee Goncalves, Maddie Mogen, Ethan Chapin and Xana Kernodle were found stabbed to death inside the off-campus rental home on Nov. 13. No suspect has been named yet.

Moscow police removed many of the victims’ personal belongings from the residence so they could return them to their families on Dec. 7.

“They’ve gone through and processed all of the biohazards that they think are there … probably pulled up carpet, pulled up drywall, anything that they think that they will need in the future, or anything that they think that they will need right now in terms of successfully prosecuting this case,” Walder said.

Recently, NewsNation’s Brian Entin explored the Idaho killer’s possible escape routes. Walder said this was likely something police did as well.

“It’s really one of the first things that you do in terms of processing a crime scene. You are looking for any entry routes or egress routes,” she said. “We have to remember: Walkthroughs are evidence just like that biological evidence.”