Washington - Texas executed a confessed murderer of five people on Wednesday, its 499th inmate to be put to death since capital punishment was reinstated in the United States nearly four decades ago.
Just two days before his 44th birthday, Elroy Chester was put to death by lethal injection at the Huntsville prison.
He was pronounced dead at 19:04 (0004 GMT Thursday), 27 minutes after the lethal drugs flowed, the Texas Department of Criminal Justice said.
Moments before the lethal injection, Chester turned to the family of one of his victims, firefighter Willie Ryman, and said he was sorry for "taking your loved one", according to prison authorities. He then began to sing softly to himself as one of his victims sobbed quietly in the back of the witness room.
He had confessed to murdering Ryman and four others during a crime spree. Ryman was killed in February 1998 when he interrupted Chester sexually assaulting the firefighter's teenage nieces during a break-in at their home.
During his 14 years on death row, Chester had made repeated appeals for clemency on the basis of mental retardation.
Texas responsible for third of executions
But the Supreme Court refused to intervene in his case.
The death penalty was reinstated in the United States in 1976. Texas resumed executions in 1982 and it alone is responsible for more than a third of US executions.
In Florida, authorities executed William van Poyck, aged 58, an hour before Chester for murdering a prison guard in a failed attempt to free another inmate.
The other prisoner, James O'Brien, was stomped to death in prison in 1999. Although seven prison guards were charged with his death, none of them was convicted.
Van Poyck's executions was the state's third this year.
Florida has 405 detainees on death row, more than any other state except California, which has 725 inmates and halted executions in 2006.