"I wish I could have done more to save Robert. I didn't kill anybody, but Ron Richardson and James Acker did."
Hannon described Mr Carter as "a good man, and a good friend" and said he "let him down when he needed me most".
"As far as Brandon Snider, I think that everyone knows what he did to get this ball rolling," Hannon said.
"I'm sorry things worked out like this. The way it did."
But at least one person watching on wasn't buying it. According to Mr Angel, a relative of one of the victims responded by saying "f*** you" and waving goodbye as the execution got underway.
The execution was carried out shortly after the US Supreme Court denied a pair of last minute appeals by lawyers for the inmate.
A Department of Corrections spokeswoman said Hannon rose at 2.30am on the day of his execution. His wife paid him a final visit. His final meal reportedly consisted of short beef rib, potato, a roll and some vanilla ice cream. He also drank some tea.
Hannon, who was convicted of slashing one man's throat and fatally shooting another in 1991, was the third inmate put death since the state resumed executions in August, following changes made to its death penalty sentencing law.
The law now requires a unanimous jury vote for a death sentence. The US Supreme Court had previously found that Florida's old sentencing law, which did not require unanimity, to be unconstitutional. However, the new sentencing law did not affect Hannon's case because the state's high court ruled that those decided before 2002 were not eligible for relief.
It was in January 1991 when Hannon and two other men went to Snider's apartment in Tampa.
Hannon's friend, Jim Acker, initially attacked Snider with a knife, according to authorities. Prosecutors said the attacks were motivated by Snider's vandalising of Acker's sister's apartment. Snider was "eviscerated" by the initial stabbing, according to court documents, and Hannon sliced his throat, nearly cutting off the victim's head.
Snider's roommate, Robert Carter, was also home and fled the violence to an upstairs bedroom, where Hannon dragged him out from under a bed and shot him six times, the jury found.
Hannon's jury recommended death unanimously after finding him guilty of both killings.
His requests for a halt to his execution to the Florida Supreme Court have been denied.
Hannon had asked for a new sentencing phase, citing recent changes to Florida's death sentencing system.
Florida Supreme Court Justice Barbara Pariente, who dissented from the rest of the court, wrote that the jury was not given enough information to make an informed decision in Hannon's sentencing phase.
Hannon not the only one executed
Hannon was executed just hours before Mexican citizen Ruben Ramirez Cardenas, 47, was given a lethal injection after several federal court appeals failed to halt his punishment for the 1997 killing of Mayra Laguna.
Cardenas was on death row in Texas before he was executed Wednesday night for the slaying of his 16-year-old cousin who was abducted from her family's apartment and fatally beaten.
Her body was found in a canal near a lake in the Rio Grande Valley in far South Texas.
Asked by the warden to make a final statement, Cardenas replied, "No, sir." As the lethal dose of pentobarbital was administered, he took a couple of breaths and then started snoring. After less than a minute, all movement stopped. Twenty-one minutes later, at 10:26pm CST, he was pronounced dead, making him the seventh convicted killer put to death this year in Texas, which carries out capital punishment more than any other state.
In a handwritten statement released afterwards, Cardenas thanked his family, attorneys and the Mexican consulate for their help.
"Now! I will not and cannot apologise for someone elses crime, but, I will be Back for Justice," he wrote. "You can count on that!"
His punishment was delayed for about four hours as last-ditch appeals for the former security guard focused primarily on efforts to have trial evidence undergo new DNA testing.
Ms Laguna's sister, Roxana Jones, said she had waited 21 years for justice to be served.
"Words can't begin describe the relief it feels to know that there is true peace after so much pain and sorrow," she said in a statement released by prison officials. "Mayra can be remembered as loving, caring, funny and dimples when she smiled. She will continue to watch over family and friends."
