A man whom police think was seen with a missing, mentally challenged Pittsburgh teenager earlier this week has shown up in Arizona.

Aaron Martens, 27, arrived in Flagstaff, Ariz., on a Greyhound bus Saturday morning. Pittsburgh police had found his car at the downtown Greyhound station on Wednesday.

Flagstaff police who questioned Martens say he told them he was alone on the bus and he claims to have no knowledge of Jamaur Jackson, 18, who has been missing from his Sheraden home since Tuesday morning.

Two waitresses at J. Clark's restaurant in Pittsburgh's North Hills told police they saw Martens and a woman with Jackson this week. Martens said he wasn't at the restaurant, according to Flagstaff police.

Jackson is black, 5 feet 8 inches tall and 170 pounds. He was wearing a white T-shirt, light blue jean shorts, and blue and black Nike sneakers when he disappeared from Litchfield Street around 8 a.m. Tuesday.

The woman who was allegedly seen with Jackson at J.Clark's is described as white, between 20 and 25 years old, with a large tattoo on her right shoulder. She is about 5 feet 7 inches and 130 to 135 pounds, and was wearing a black halter top with tan pants.

Anyone with information about Jackson or the unidentified woman is asked to call Pittsburgh police at (412) 665-4020.