Running back Rushel Shell won't be returning to Pitt, a source told ESPN.com on Monday.

Shell asked for his release in April and decided to transfer to UCLA. But Shell never enrolled at the school and instead recently asked the Pitt coaching staff about returning to the Panthers. The door was never open for Shell to return, the source said.

Shell, who arrived at Pitt in 2012 as one of the top running back prospects in the country, would have been the featured back for the Panthers in 2013. But Shell asked for time away from football during spring practice to "work through some challenges."

On April 2, Pitt formally announced Shell had decided to transfer.

Shell is from nearby Aliquippa, Pa., and has twin daughters living in Pennsylvania. The Los Angeles Times reported Shell changed his mind about UCLA because he felt the distance was too great.