PORTSMOUTH, Virginia (Reuters) - A man who admitted to strangling two fellow prison inmates and threatened to continue killing until he received the death penalty was executed in Virginia on Wednesday, the first time the state has used the electric chair in nearly three years.

Robert Charles Gleason Jr., 42, was pronounced dead at 9:08 p.m. (0208 GMT on Thursday), Virginia Department of Corrections spokesman Larry Traylor said.

Gleason was the first inmate to be executed this year in the United States, according to the Death Penalty Information Center, a group that tracks capital punishment cases.

(Reporting by Matthew A. Ward; Writing by Kevin Gray; Editing by Eric Beech)