William Van Poyck, Fla. man, executed for murdering prison guard during 1987 escape attempt

(CBS/AP) STARKE, Fla. -- A Florida man was executed Wednesday night for the murder of a guard during a botched 1987 prison van ambush intended to free an imprisoned friend.

William Van Poyck, 58, was pronounced dead at 7:24 p.m., 23 minutes after the injection process began at Florida State Prison. 

"Set me free," were his final words.

Van Poyck's case garnered international attention because he published three books and maintained a blog while on death row. He even wrote recently about his pending execution.

"He's finally free from those prison walls," Lisa Van Poyck, the inmate's sister, said as she stood among the protesters standing across the street from the building where her brother was executed.

The family of the slain guard, Fred Griffis, has said in interviews that they were frustrated that news stories focused on Van Poyck, the crime and his writings - and not Griffis.

"It's been a very traumatic experience," said Norman Traylor, the victim's cousin.

William Van Poyck and Frank Valdes ambushed a prison van outside a West Palm Beach doctor's office in a failed attempt to free James O'Brien - with whom they'd served time. Griffis was fatally shot after he threw the van's keys into the bushes to foil the escape.

Van Poyck and Valdes were captured following a car chase. Steve Turner, one of the corrections officers ambushed that day, spoke after the execution on Wednesday.

"Justice has prevailed," he said. "They can close the book." In his appeals, Van Poyck argued that Valdes fired the fatal shots and that if the jury had known that, he wouldn't have been sentenced to death. The Florida Supreme Court last week rejected Van Poyck's latest appeal involving Valdes' widow, who says her husband told her he was the gunman.

The justices noted that Van Poyck planned the escape attempt and that he and Valdes carried loaded weapons.

In 1999, Valdes was stomped to death in prison. Seven guards were charged with his death, but none were convicted.

Following Valdes' death, Van Poyck was moved to Sussex State Prison in Virginia for his safety. That's where he wrote a 324-page autobiography, "A Checkered Past: A Memoir," saying his purpose was not to elicit sympathy but "to put a human face on me and convicts in general."

Van Poyck went on to write two novels. He won awards for his writing and kept a blog since 2005 by writing letters to his sister, who posted them online.

"He is deeply remorseful for the ending of Fred Griffis' life," Lisa Van Poyck told The Associated Press on Tuesday. "He is guilty of a crime of trying to break somebody out of a prison transport van - he had no intention of hurting anyone."

In his blog, Van Poyck wrote in recent entries that he has received dozens of letters a day regarding his pending execution. 

"I am not unusual in wanting to believe, at the end of my line, that my life counted for something good, that I had some positive influence on someone, that my life made a difference, that I was able to at least partially atone for the many mistakes I made earlier in life," he wrote.

Griffis family members planned a gathering Wednesday for quiet reflection about Fred Griffis' life.

"When he was murdered, it basically ripped a hole in the family's heart that's never really healed," said brother Ronald Griffis.

Ronald Griffis said his brother was always looking out for others. He was released on medical discharge after his first tour in Vietnam, but re-enlisted for two more because he felt he could help. In his final moments, he was determined not to let a killer escape.

Said Ronald Griffis: "I knew that even atthe end, he was still my brother, he was still Freddy, that's who he was. He protected others."