Police found a stolen purse inside the boy's Spider-Man backpack, the Philadelphia Daily News reported. The boy was also used as a "pawn" to steal two credit cards from another student, police said.
Bernard Davenport, who reportedly also uses the name Kevin Long, was arrested Thursday at Houston Hall on the Penn campus. His sister, Tondeala Davenport, escaped -- but turned herself in Saturday afternoon to face charges that include theft and child endangerment.
Lt. John Walker of the Philadelphia police told WCAU-TV the boy quickly spilled the beans.
"They brought this kid in here -- he was the cutest little kid," Walker said. "Talking to us and joking around, and asking for potato chips and pretzels, and so on and so forth."
The boy is in the care of relatives.