Arkansas has executed Kenneth Williams, the fourth inmate it has put to death in eight days.
Williams was executed by lethal injection on Thursday night at the Cummins Unit prison in Varner.
A prison spokesman said three minutes after the injection began, Williams shook for about 10 seconds before being pronounced dead at 11.05pm.
A reporter from Associated Press who witnessed the execution said Williams had been "lurching, convulsing, coughing and jerking".
The 38-year-old was executed for the death of former deputy warden Cecil Boren, 57.
Williams had murdered Mr Boren after escaping from prison in 1999.
He had stolen Mr Boren's truck and, during a chase in southern Missouri the next day, he had crashed into another vehicle, killing the driver, 24-year-old Michael Greenwood.
At the time of his escape from jail, he had been less than three weeks into a life sentence for the death of college cheerleader Dominique Hurd.
After jurors had spared his life in Ms Hurd's case, he turned to the girl's family and taunted them, saying: "You thought I was going to die, didn't you?"
In his final statement read from the death chamber, Williams said: "I extend my sincerest of apologies to the families I have senselessly wronged and deprived of their loved ones.
"I was more than wrong.
"The crimes I perpetrated against you all was senseless, extremely hurtful and inexcusable."
One of Mr Boren's daughters, Jodie Efird, who watched the execution, said: "Any kind of movement he had was far less than his victims."
A spokesman for the attorney general said Mr Boren's family had thanked authorities for the "flawless care of this matter".
But Mr Greenwood's family have said they have forgiven Williams and even arranged for the killer's daughter to visit him before his execution.
Mr Greenwood's daughter Kayla told the Springfield News-Leader: "I don't believe killing someone after someone's death has already happened is God's way."
She had urged Arkansas Governor Asa Hutchinson to spare Williams.
After the execution, Mr Hutchinson said the "long path of justice ended tonight" and the state's residents could "reflect on the last two weeks with confidence that our system of laws in this state has worked".
"Carrying out the penalty of the jury in the Kenneth Williams case was necessary.
"There has never been a question of guilt."
Williams' lawyers said he had sickle cell trait, lupus and brain damage, arguing the lethal injection drugs could subject him to an exceptionally painful execution, in violation of the US Constitution.
Arkansas had planned eight executions over an 11-day period before one of its lethal injection drugs expires on Sunday but courts issued stays for four of the inmates.
The executions this month were the first in the state for 12 years.