FORT MADISON, Iowa (AP) — An Iowa man who spent 48 years in prison for killing a 10-year-old girl has died in custody. The Iowa Department of Corrections says Robert Anthony Williams died Wednesday of natural causes at the State Penitentiary in Fort Madison. He was 73. Williams was convicted of killing Pamela Kay Powers, of Urbandale, Iowa, on Dec. 24, 1968.

The girl was abducted from the downtown Des Moines YMCA while attending her older brother’s wrestling tournament with her family. Williams led police to the girl’s frozen body along a gravel road near Mitchellville two days after she was killed.

While incarcerated, Williams filed several of his own appeals and his case went to the U.S. Supreme Court twice. But he failed to regain his freedom.