Jon-Christopher Clark is not considered a suspect or person of interest in the case. But Phoenix Police did execute a warrant to search his phone, car and residence on Friday.
He was then arrested and charged with more than 20 counts of aggravated identity theft and forgery, HuffPost reported.
Clark is the last person to have seen the 19-year-old before she vanished on Aug. 4.
He picked her up from work that day and, back at their apartment, "we just started getting into a little bickering and then she got upset and then she left" he told The Arizona Republic.
Her only other subsequent communications were a text to Clark, referencing their earlier argument, and another to her roommate, Destiny Hall-Chand, which said "she was picked up by someone, someone that she had met at the store a couple of days ago" the roommate told The Republic.
No one has heard from Bergman since.
Clark told The Republic he had "nothing to do with anything that's going on, I love Kiera with all my heart, I want her to come home."
Bergman's parents, Kiersten and Chris Bragg, have said they suspect Clark was involved in the disappearance. He said he believes the family wants "someone to blame, someone to bring them answers and bring conclusion to everything."
Phoenix police consider the disappearance suspicious.
Clark was first detained by police and questioned last week, before being released. He told HuffPost he felt "like they were treating me like a suspect."
Clark was then arrested on Friday and appeared in court this weekend, He is being held on $25,000 bond, according to HuffPost, and due back in court on Friday.
"We just want her back," Chris Bragg told HuffPost. "We want to find her before anything bad or anything worse happens to her."