SALT LAKE CITY, Utah -- Police have filed charges of aggravated murder against a man suspected of killing missing Utah college student Mackenzie Lueck, a native of Southern California, Salt Lake City Police Chief Mike Brown said in a Friday news conference.
The suspect, identified by Brown as Ayoola Ajayi, also faces charges of aggravated kidnapping, obstruction of justice and desecration of a body.
Their investigation showed Lueck and Ajayi's phones were both in the park within less than a minute of each other, Brown said. This was approximately the same time that Lueck's phone stopped receiving data or location services.
On Wednesday, as detectives searched Ajayi's home and property, Ajayi's neighbors told police they saw him using gasoline to burn something in his backyard on June 17 and June 18, according to Brown.
"A forensic excavation of the burn area was conducted, which resulted in the finding of several charred items that were consistent with personal items of Mackenzie Lueck," Brown told reporters.
Police also discovered charred material that was determined to be female human tissue, he said. The DNA of the human tissue was found to be consistent with Lueck's DNA profile.
Lueck, a 23-year-old University of Utah student from El Segundo in Los Angeles, flew in to Salt Lake City International Airport from a family funeral in California and texted her parents at 1 a.m. when she landed.
Airport surveillance footage showed her rolling her luggage past a baggage carousel in the early morning hours.
She then took a Lyft to Hatch Park in North Salt Lake City, where she was last seen.
"Mackenzie was met at Hatch Park by an individual in a vehicle,"
Salt Lake City Police Assistant Chief Tim Doubt told reporters Monday that the Lyft driver "stated that Mackenzie did not appear to be in any type of distress."
The rideshare company confirmed the route Lueck took and the app said that it showed no irregularities.
"We recognize how scary this must be for those who know and love Ms. Lueck," Lyft said. "The safety of our community is fundamental to Lyft and we are actively assisting law enforcement with their investigation."
Instagram account active after Lueck vanished
Lueck's Instagram account has been active since she disappeared. An account bearing the name "Kenzie Lueck" followed another Instagram user on or about Wednesday, CNN verified. That user has not replied to CNN's request for comment.
It's possible another individual accessed Lueck's account and is responsible for the activity.
The account belongs to Lueck, her sorority sister Kennedy Stoner confirmed. Lueck's friends have shared information regarding the account's activity with Salt Lake City police, Stoner said.
Investigators have been looking into the account's activity, along with the rest of the case's "digital footprint," Brown confirmed Thursday.
"This is a digital forensic investigation," he said. "This is covering computers, cell phones, IP addresses, URLs, texting apps."
Friends and family worry
Lueck's family and friends told police that it was unusual for them to have not heard from her.
She was scheduled to fly to Los Angeles on June 23 but missed the flight.
Friend and sorority sister Ashley Fine told CNN affiliate KSL that Lueck also has missed exams.
"She's extremely dedicated. She would never miss her midterms or anything like that," Fine told the Salt Lake City TV station. "She hasn't been home. She didn't show up to work, or anything."
Brown spoke to her father and said he could "feel the heartache and the pain and the suffering in his voice as we spoke."
"And my commitment to Greg was we would do everything within our power, the Salt Lake City Police Department, to bring Mackenzie home," Brown said. "And that is our charge and that we are committed to do."