STARKE — David Alan Gore, one of the most vicious serial killers in Florida history, was executed Thursday after spending 28 years on death row.After an excruciating series of execution delays, two dozen relatives and law enforcement personnel watched in silence as Gore succumbed to a lethal dose of chemicals. Prison official Tim Cannon, after speaking briefly to the governor's office by phone, announced that the death sentence was carried out at 6:19 p.m.Gore, 58, who killed six women in Indian River County in 1981 and 1983, repeatedly sought to use the judicial system to prevent his execution and described an uncontrollable urge to kill in a book about serial killers.But a few minutes before his death, as he lay strapped to a gurney in the death chamber, covered in a white sheet, he said: "I'm sorry. I've had remorse. ... I'm not the man I was back then. I don't fear death." The execution took 10 minutes.Gore was condemned to death for the rape and murder of 17-year-old Lynn Elliott, who was hitchhiking to the beach with a friend on a summer day in 1983 when Gore stopped and picked them up.After assaulting Elliott repeatedly at the home of his vacationing parents, Gore shot the girl in the head as she ran down his driveway with her hands tied. A boy riding by on his bicycle witnessed the killing and called 911.On Thursday evening, Elliott's father, Carl, sat in the center of the front row of a small observation room as Gore lay a few feet away, visible through a large window. Elliott was Gore's final victim. The others were Hsiang Huang Ling, 48, and her daughter Ying Hua Ling, 17; Judy Kay Daley, 35; Angelica LaVallee, 14, and Barbara Ann Byer, 14. Gore's cousin and accomplice Fred Waterfield is serving two consecutive life sentences for his role.Gore was tried and convicted of Elliot's slaying in Pinellas County because of intense pretrial publicity in Vero Beach.An author who corresponded for years with Gore, Pete Earley, detailed in a book that Gore felt an uncontrollable urge to kill and expressed no remorse for his killings. The book Serial Killer Whisperer was brought to Gov. Rick Scott's attention by Vero Beach newspaper columnist Russ Lemmon shortly before Scott signed Gore's death warrant. Forty other inmates have been on death row longer than Gore.For years, Gore's attorneys filed appeals to delay or reverse his execution. A federal judge vacated Gore's death sentence in 1989 after Gore claimed he was too drunk to have known what he was doing the day of the Elliott killing. Another judge reimposed the death penalty three years later. In his final appeal, Gore raised a flurry of legal issues in an effort to stay alive, from the subsequent disbarment of a former attorney to his length of time on death row. In a decision Monday, the Florida Supreme Court rejected all of his arguments. Gore, one of 400 prisoners on Florida's death row, became the 73rd person to be executed in Florida since the state re-instituted the death penalty in 1976. He was the fourth person to be executed since Scott became governor 16 months ago."This was an individual whose crimes were heinous," Scott said earlier Thursday. "He was convicted and sentenced to death." The governor rejected calls by Florida bishops who oppose capital punishment to spare Gore's life. "I can tell you, I pray about it," Scott said. "I pray for his family. I pray for his victims. It's not something I take lightly."