Salt Lake City — Salt Lake City police on Thursday spent hours collecting bags of items they hope could lead them to finding 23-year-old Mackenzie Lueck. They also interviewed, then released, the homeowner, a man they describe as a person of interest.

Among the items not found, is a mattress that police said was given away online. They're hoping to track down whoever claimed it.

Salt Lake City Police Chief Mike Brown said the man was not in custody and he declined to name him. But authorities have said that they believe that the house has a connection to the disappearance of Lueck, without providing details.

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CBS affiliate KUTV reported that the homeowner is a Utah State University graduate who served in the military and is a freelance model, according to his social media pages.

Police generally use the term "person of interest" for someone they believe might have information about a crime that leads to a suspect, or may be eventually become a suspect.

"Obviously, we are treating this with a high degree of care and caution as it is an open case," Assistant Police Chief Tim Doubt told reporters earlier Thursday. "Given the nature of this case, we just don't want to make any mistakes. We will continue to follow leads until this is resolved."

Lueck disappeared after taking a Lyft on June 17 from the airport to a park, where police have said she met someone at about 3 a.m. and did not seem distressed. They have said the Lyft driver had no connection with her disappearance

The home that police searched is about 5 miles from that park. The owner of the home that was searched rented part of it to short-term renters using home sharing rental sites, said neighbor Tom Camomile.

Lueck's close friend, Ashley Fine, uploaded a new video Thursday morning onto the "Find Mackenzie Lueck" Facebook page saying she believes her friend is still out there. She pleaded with people to call police with any information that could help locate Lueck.

"Everyone around the country is looking for you. We're advocating for you, we're fighting for you, and we're going to bring you home safely," Fine said.