(NewsNation) — On Tuesday, investigators returned to the house in Moscow where four University of Idaho students were found stabbed to death last month. Here is what we know:

Investigators at the house were carrying a black case, and were inside the residence for about 20 minutes.

Police have been probing what happened there since Kaylee Goncalves, 21; Madison Mogen, 21; Xana Kernodle, 20; and Ethan Chapin, 20 were found dead Nov. 13 in the rental home. Kernodle, Goncalves and Mogen were roommates. Chapin and Kernodle had been dating. All four died from stab wounds, and were likely asleep at the time of the attack, according to preliminary findings by a county coroner.

No suspect has been identified so far, but police have cleared a list of people. As of Tuesday afternoon, investigators have conducted over 250 interviews, and gotten 7,650 email tips and 4,313 by phone, Moscow police said in a news release. Police put out a public call last week for information about a white Hyundai Elantra they believe was in the area of the house near the killings.

The news release said police are aware of a Hyundai Elantra located in Eugene, Oregon, and they are working with the local jurisdiction to see if the vehicle is related to the case in Moscow. Eugene Police told NewsNation that there is no information to indicate the vehicle is related to this investigation, but they still let Moscow police know so they could review it.

Despite the upcoming holidays, Moscow Police Department Officer Robbie Johnson said the investigation isn’t winding down. And Moscow Police Chief James Fry says his command team has 94 years of combined experience.

“Be assured this investigation is the Moscow Police Department’s,” Fry said. “We are going to follow through with this.”

If you have information that could be helpful for law enforcement, you can contact them at their tip Line: 208-883-7180, email tipline@ci.moscow.id.us, or go online to fbi.gov/moscowidaho.