A Maine State Prison inmate has been charged in the beating death of Lloyd Franklin Millett, a fellow prisoner who had been serving two life sentences for killing a pair of women in the Lewiston area.

Frank Higgins, a 49-year-old already serving time for murder, was indicted by a Knox County grand jury on a new charge of murder.

Millett, 51, was beaten at the prison on May 24, investigators said. He was taken to Eastern Maine Medical Center in Bangor where he died on June 7. Police and prison officials have been investigating the killing since.

Although police did not provide details of Millett’s death, other inmates said Millett was not well-liked at the prison. He was regarded as a bully and a snitch, according to a pair of prisoners who wrote the Sun Journal.

“Inmate Frank Higgins is allegedly being investigated for bashing Millett’s head with a wood clamp,” one inmate wrote, days after Millett died. “Another inmate lost his job in wood shop for his involvement.”

A former prison worker described Millett as “in my opinion, the most dangerous inmate out of the 650 we had at that time.”

Investigators have not said if there was any personal relationship between Higgins and Millett. The pair did have one thing in common, however: each was serving time for the murder of women.

Higgins was serving 45 years for killing a Kenduskeag woman inside her home in 1999. His victim, Katherine Poor, was raped and then stabbed several times in the neck.

Millett was serving life sentences for the 1995 rape and murders of women in Turner and Lewiston during a weekend killing spree.

On Nov. 6, 1995, the body of Rachelle Anne Williams, 33, of Gorham, N.H., was found in a field outside the Ramada Inn in Lewiston. Williams had been socializing with co-workers after a weekend conference when Millett snatched her and dragged her into a field, police said. Williams was raped and strangled.

While police were investigating that killing, the body of 39-year-old Terrie Lizotte was found inside a closet at Millett’s trailer in Turner. Police soon linked the two murders together and investigators had their suspect when Millett turned himself in.

A native of Rumford, Millett pleaded guilty to both murders. He was sentenced to 70 years in prison for Lizotte’s murder and a concurrent life sentence for killing Williams.

Millett had a lengthy criminal record before the murders, including a 1991 rape conviction for which he was sentenced to eight years in prison. For a time, cold case detectives considered Millett in a number of unsolved murders in various parts of the state.