Before he was put to death by lethal injection at 6:32 p.m. EST at the state prison in Starke for the 1992 slaying of Trooper Jimmy Fulford, Howell made a statement that ran more than 2 minutes, the Tallahassee Democrat reported.
"I would like to apologize to the Fulford family for what happened back in 1992," Howell said.
The newspaper said he prayed as he was given the lethal drugs.
Authorities said the member of the Jamaican Posse gang used bomb-making skills he learned in the Army to rig a microwave oven with explosives and hired another man to deliver the homemade bomb to Tammie Bailey, a woman who could tie him to the slaying of a drug dealer.
But while delivering the gift-wrapped, booby-trapped oven to Bailey, Lester Watson was stopped for speeding by Fulford and it exploded while he was examining it.
"So I'm sorry about that," the Democrat reported Watson said while on a gurney with an IV in his left arm.
Howell visited with his wife and grown daughter during the week but asked they not be at his execution. None of Fulford's family attended, a corrections spokeswoman said.
Highway Patrol Maj. Mark Welch said it was a time to honor "one of its most courageous and brave officers" and to "let this serve as a reminder of the dangers that law-enforcement officers face each and every day they put on their uniform and leave their homes and their families behind."
State Attorney Willie Meggs said he hoped the execution would bring the Fulford family closure.
"I think justice was done. It was the right thing to do," he said.