A man has been arrested and charged with murder in the disappearance of University of Utah senior Mackenzie Lueck, Salt Lake City Police Chief Mike Brown said at a press conference Friday.

Ayoola Ajayi, reportedly a 31-year-old former Army IT specialist, was charged with aggravated murder, aggravated kidnapping, obstruction of justice and the desecration of a body, police said.

Authorities conducted a search of Ajayi’s property on Wednesday, where they found charred personal items and “female human tissue” in the backyard, Brown said. According to the police chief, DNA from the tissue matched DNA from Lueck’s personal items. Ajayi’s neighbors told police they had seen him burning something in the backyard on June 17 and 18.

“This is one of the most difficult phone calls I’ve ever made as both Greg and his wife, Diana, were devastated and heartbroken by this news,” Brown said Friday.

At around 2 a.m. on June 17, Lueck arrived at the Salt Lake International Airport after attending a family funeral in California. Surveillance footage from the airport shows the 23-year-old walking through the terminal, rolling her luggage past a baggage carousel, and exiting the airport’s departure area to meet a Lyft driver.

According to police, Lueck then took the Lyft to Hatch Park in North Salt Lake. The driver dropped her off at around 3 a.m.

Brown said all communications from Lueck ceased at 3 a.m. and that her last conversation was with Ajayi.

Ajayi told police he texted Lueck on July 16, but didn’t communicate with her after that. According to Brown, Lueck and Ajayi’s phones were both traced back to the park within a minute of each other the night she disappeared.

Ajayi also denied ever having seen a picture of Lueck despite having multiple photos of her on his phone, police said.

“Mackenzie was met at Hatch Park by an individual in a vehicle,” Salt Lake City Police Assistant Chief Tim Doubt told reporters Monday. “The Lyft driver left Mackenzie at the park with that person and stated that Mackenzie did not appear to be in any type of distress.”

Earlier this week, Lyft confirmed that Lueck’s route was not out of the ordinary and ended at the destination she entered into the app. After dropping the 23-year-old off, the driver continued his shift and picked up other customers, the company said.

Her family filed a missing-persons report on June 20. Three days later, Lueck missed a flight to Los Angeles and a midterm exam, a move her sorority sister said is out of character.

“She would never miss her midterms or anything like that,” Ashley Fine told KSL, adding that Lueck is “extremely dedicated.”

At the Friday press conference, Lueck’s uncle asked members of the media to respect the family’s privacy during this difficult time.

Christina Judd, the Salt Lake City Police Department’s communications director, said Ajayi will be held at the Salt Lake County Jail while waiting for the conclusion of the investigation and the “prosecution phase.”