By Tony Hanson

PHILADELPHIA (CBS) — A former priest who admitted sexually assaulting a 5th-grade boy in the Philadelphia clergy sexual abuse scandal today recanted during the trial of another priest and a former lay teacher charged with sexually assaulting the same boy.

Defrocked priest Edward Avery pleaded guilty last year to sexually assaulting the same boy who has also accused the defendants now on trial: Father Charles Engelhardt and Bernard Shero (see related story).

But Avery, called to the witness stand from prison where he is serving a 2½-5 year sentence, told the jury today that he never assaulted the boy, didn’t even know him, and only took the plea deal to avoid the possibility of a conviction and a sentence that might have kept him in prison for life.

Avery, called by the prosecution, quickly became a so-called “hostile” witness, and during questioning that was at times heated, he conceded that he had admitted to the crimes in court — swore he committed them.

Prosecutors had been depending on Avery’s testimony to cement their case against Engelhardt and Shero (see related story).