A man was executed in Indiana for the murder of a police officer in 2000, the prison department said, one of three executions to be carried out in the United States this week.
Benjamin Ritchie, 45, was put to death by lethal injection at the Indiana State Prison in Michigan City after being sentenced for the murder of officer Bill Toney, in the second execution in the midwestern state since 2009.
Mr Toney, a father of two, was shot to death after pursuing a van that had been stolen by Ritchie and another man from a petrol station in the town of Beech Grove.
Ritchie was pronounced dead at 12.46am (5.46am Irish time) this morning, about 45 minutes after the execution process began, the Indiana Department of Correction said in a statement.
A second execution, of a man who pleaded guilty to killing a shop worker by setting her on fire, is scheduled for later today in Texas.
Matthew Johnson, 49, is to die by lethal injection at the Texas State Penitentiary for the 2012 murder of Nancy Harris, a 76-year-old grandmother.
Johnson admitted at trial to pouring lighter fluid on Ms Harris and setting her alight during an early morning robbery of a shop in Garland, Texas.
Ms Harris suffered severe burns and was taken off life support five days later.
The other execution scheduled this week is in the southern state of Tennessee.
Oscar Smith, 75, is to be put to death by lethal injection on Thursday for the 1989 shooting and stabbing murders of his estranged wife, Judy Smith, and her two sons, Chad and Jason Burnett.
There have been 17 executions in the United States this year: 13 by lethal injection, two by firing squad and two using nitrogen gas.
The death penalty has been abolished in 23 of the 50 US states, while three others - California, Oregon and Pennsylvania - have moratoriums in place.
President Donald Trump is a proponent of capital punishment and called on his first day in office for an expansion of its use "for the vilest crimes."
