(CNN) - More than a week has passed since Mackenzie Lueck disappeared.
The 23-year-old hasn't been seen or heard from since returning to Utah, from California, on June 17. Lueck, a senior at the university of Utah, vanished without a trace.
"She could be anywhere; we don`t know if she's in the state of Utah," said Ashley Fine, a sorority sister. "This could be a nationwide search for her."
She landed at Salt Lake City International Airport after a family funeral.
A Lyft driver dropped her off at Hatch Park at around 3 a.m., where she was met by an unknown person. Salt Lake City Assistant Chief Tim Doubt told KUTV the driver reported Lueck did not appear to be in any distress.
And that’s the last anyone has seen or heard from her. Lyft and the driver have cooperated with the investigation, and police have cleared the driver as a suspect, Doubt told the Associated Press.
The Lyft driver, whose identity has not been revealed, gave other rides after dropping off the woman, he said.
"For her not to reach out to me, Snapchat, Instagram, anything is very unlike her, very uncommon," said friend Kennedy Stoner. "She's usually in touch with me almost every day."
“A lot of tips are coming in,” Doubt said. “We have about six detectives staffing that line right now, plus other detectives who are going out and answering those tips and trying to find out what’s happening.”
As the search goes on, family and friends are hoping for a happy ending.
"Kenzie, if you can hear this, we are all worried and looking out for you 24/7," Stoner said.
Police believe Lueck's phone has been shut off since the day she disappeared, which is why they can't pinpoint a location.
A tipline for her has been established: 801-799-4420.