Death row inmate Troy Davis has been executed in the US state of Georgia for the fatal shooting of policeman Mark MacPhail in 1989.
Davis' death was delayed for hours while the US Supreme Court considered an eleventh-hour appeal for clemency.
The 42-year-old's case was heavily disputed after most of the witnesses recanted or changed their testimony.
Inside the jail in Jackson, Georgia, Davis protested his innocence until the end as supporters protested outside.
There was a heavy police presence as hundreds held a vigil awaiting news from the US Supreme Court.
I am innocent," Davis said moments before he was executed. "I did not have a gun."
Davis was convicted in 1991 of killing MacPhail, an off-duty police officer, but always maintained he was innocent.
The US Supreme Court judges took more than four hours to issue their rejection of the final appeal, an unusually long time for such a ruling.
The application for stay of execution of sentence of death presented to Justice [Clarence] Thomas and by him referred to the Court is denied," it read.
Davis continued to protest his innocence in the death chamber.
Davis's execution date had already been moved several times
"For those about to take my life, may God have mercy on your souls.
May God bless your souls.
"All I can ask... is that you look deeper into this case so that you really can finally see the truth. I ask my family and friends to continue to fight this fight."
Davis was pronounced dead at 23:08 (03:08 GMT Thursday), 15 minutes after the lethal injection began.
