Police executed a search warrant Wednesday at the home of a man they consider a “person of interest” in the case of missing University of Utah student Mackenzie Lueck.

The homeowner was not in custody and had spoken with detectives, Salt Lake City Police Chief Mike Brown said Thursday at a news conference. He declined to name the owner of the home in the city’s Fairpark neighborhood or to say how cooperative he had been.

Detectives collected several pieces of evidence from the home and are testing them, Brown said. Police also are searching for a mattress and box spring they say were given away from the home last week and could be related to Lueck’s disappearance.

Investigators carried shovels into the home’s backyard to dig around a fire pit, the Salt Lake Tribune reported. They later carried bags out of the house and towed a car, the Tribune said.

Neighbors told the Tribune that the owner had been renting out part of his house through Airbnb and that they recently saw him burning something in his backyard.

Police consider the search for Lueck, 23, a missing-person case. They are scouring her digital communications, Brown said, including computers, cellphones and messaging apps.

“This is a very active and ongoing investigation,” Brown said. “We’re trying to balance the integrity of this investigation with what we can put out to the public. But we want to reiterate that we need the help of the public in this case.”

Lueck, who goes by Kenzie, was traveling back from her grandmother’s funeral in California when she landed at Salt Lake City Airport about 1 a.m. on June 17, the Salt Lake Tribune reported. She then took a Lyft to North Salt Lake and vanished, police said.

The ride-share driver dropped Lueck off at Hatch Park around 3 a.m. to meet an unidentified person waiting in a vehicle, Assistant Police Chief Tim Doubt said at a news conference Monday. The park is about an eight-mile drive in another direction from her home in Trolley Square on the eastern edge of downtown.

The Lyft driver said Lueck did not appear distressed when she approached the other vehicle, Doubt said.

Lueck’s route “contained no irregularities” and ended at the scheduled destination, said a Lyft spokeswoman, Lauren Alexander. She said the driver continued on to pick up other riders.

Lueck’s disappearance has concerned her friends, who said that going off somewhere without telling anyone out of character for her. One friend, Ashley Fine, said she was unaware of Lueck’s having a significant other or any reason to venture 20 minutes in the opposite direction from her home.

“She threw a birthday party for her cat, so for her not to come home to her cat is not adding up,” Fine said at a news conference Sunday.

Kennedy Stoner, a sorority sister, said it was “very unlike” Lueck not to check in with her.

“We don’t believe she would miss a midterm because she was stressed. I am positive something is wrong,” Stoner said. “I don’t believe she would go off and not contact one person.”

Lueck’s friends have handed out missing-person fliers and pleaded on Facebook for more information to assist the police.

“Kenzie, if you can hear this, we are all worried and we are looking out for you 24/7,” Stoner said. “We are not able to sleep. I cannot sleep at night knowing you are out there. Please let us know if you are safe.”

Police have designated a tip line for the search: 801-799-4420.

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