University of Utah student still missing one week after taking Lyft from Salt Lake City airport

Family and friends of a missing University of Utah student are pleading for information about her mysterious disappearance, shortly after taking a Lyft ride. Mackenzie Lueck was last seen one week ago.

Last Monday, Lueck's family says she landed at Salt Lake City International Airport after attending her grandmother's funeral in California. She took a Lyft from the airport to an address in north Salt Lake. Her family and friends say the 23-year-old hasn't been seen or heard from since.

Juliana Cauley says she's felt lost ever since her best friend disappeared. The pair met at the University of Utah where Lueck is studying kinesiology. Cauley says they hit it off from the start. 

"I've never met a person that doesn't like Mackenzie. She is the sweetest and most genuine," Cauley said. "It's not like her to go off the grid and if she did then she would tell me." She said she still calls and texts her best friend hoping that she'll pick up or respond.

Lueck was last heard from around 1 a.m. on June 17 when she texted her mom saying her flight landed safely at Salt Lake City International Airport. From there, police say, she ordered a Lyft to an address in north Salt Lake but Cauley says Lueck didn't live in north Salt Lake and she doesn't know why she went there. Her parents reported her missing three days later.

In a statement, Lyft told CBS News the safety of its community is "fundamental" and it's "actively assisting law enforcement with their investigation." Lyft says there were no irregularities in the ride Lueck took, and that it ended at the destination she entered in the app and the driver continued taking other customers immediately after dropping her off.

Lueck has also been absent from social media and Lueck's friends and her sorority sisters have been passing out flyers in Salt Lake City, hoping anyone with information will come forward.

"I would do anything to get her back. And honestly, I would trade places with her in a heartbeat just to know she's safe," Cauley said.

The Salt Lake City Police Department says Lyft and its driver have cooperated with their investigation. The department says it has not discovered anything that would lead it to believe that Lueck has been harmed.

Lueck's father told our Salt Lake City affiliate KUTV that they are working on getting subpoenas for her phone records.