(CNN) Cell phones and social media were at the heart of the investigation that led to an arrest in the killing of a University of Utah student who vanished nearly two weeks ago.

Investigators tracking her cell phone discovered that 23-year-old Mackenzie Lueck and the man expected to be charged with her murder were both in the park where she was last seen on June 17 within a minute of one another.

That was around the time Lueck's phone stopped receiving data or location services, police said.

Ayoola Ajayi, 31, was arrested Friday and is expected to be charged with aggravated murder. He also faces charges of aggravated kidnapping, obstruction of justice and desecration of a body, according to Salt Lake City Police Chief Mike Brown.

Police find her pictures on his phone

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