According to the initial police report, Sprague, of Placentia, told police the suspect allegedly "simulated a handgun in his waistband." Sprague told police he complied and said to the suspect he believed the girl was still in the backseat.
The suspect then fled with the car, apparently with the 17-year-old still inside, northbound on Santa Ana Avenue, according to the report.
Police issued a statewide Amber Alert, only to call it off by the afternoon after the girl was found in central Orange County by police, Costa Mesa Sgt. Phil Myers said.
It was unclear Monday if the Expedition or reported suspect have been found.
During the girl's alleged disappearance, she was in contact with her family via an unnamed online social networking site and said to them she was not in danger, according to police.
Police said the girl's online messages also could have indicated she may not have been in the vehicle when it was taken. Before she was found, police had tried using the website to contact her but were unsuccessful.
According to Sprague's Facebook profile page, he is a 2007 Newport Harbor High School graduate and an electrician.
The Orange County Register reported that, according to county court records, Sprague is on probation for drug and drug paraphernalia possession and was sentenced to a rehab program in April.