BOSTON (AP) — The suspect in the prison cell slaying of defrocked priest John Geoghan hated gays and planned the killing weeks in advance, a prosecutor said recently. Joseph L. Druce, a fellow inmate in the maximum security Souza-Baranowski Correctional Center, “has a long-standing phobia, it appears, toward homosexuals of any kind.... He is filled with long-standing hate,” said Worcester District Attorney John J. Conte said.

Geoghan, 68, was killed Aug. 23 in his cell while serving a nine- to 10-year sentence for assault and battery on a 10-year-old boy. He had been in protective custody since being transferred to Souza-Baranowski in April, officials said.

The former priest was accused of molesting nearly 150 boys over three decades and became a catalyst for the clergy sex abuse scandal that shook the foundations of the Roman Catholic church.

Druce is serving a life term for killing a gay man 15 years ago.

Conte said Druce had confessed to the crime. Asked if Druce seemed proud of having killed Geoghan, Conte replied: “Absolutely. No question about that.”

He also said authorities would investigate why the safeguards supposed to be in place for inmates in protective custody weren’t enough to save Geoghan.

Gov. Mitt Romney has appointed a panel to conduct an independent investigation into the death.