By Bill Cotterell and Jon Herskovitz
TALLAHASSEE, Fla./AUSTIN, Texas (Reuters) - Florida executed a convicted rapist and murderer on Tuesday, using a new drug in its lethal injection procedure that has been challenged in court by death row inmates who say it would leave them in extreme pain.
Darius Kimbrough was pronounced dead at the state prison in Starke, Florida, at 6:18 p.m. EST (2318 GMT), 18 minutes after the lethal injection procedure got underway.
The execution of Kimbrough, which followed the rejection of his final appeal by the U.S. Supreme Court, was the 33rd in the United States this year.
It was to be followed later in the evening by the execution in Texas of Jamie McCoskey, who was convicted of kidnapping a couple in 1991 in Houston, raping the woman and stabbing her fiancé to death.
Kimbrough, 40, was sentenced to die for killing Denise Collins, an aspiring artist, after he broke into her Orlando, Florida, apartment and sexually assaulted her. She was found barely alive on her bathroom floor in October 1991. Collins died days later.
Kimbrough made a handwritten plea to the Florida Supreme Court questioning the use of DNA evidence in his conviction and a new sedative being used in executions in the state. The high court last week rejected his appeal as did the U.S. Supreme Court.
His execution was the second in the state using midazolam as the first of three drugs administered in lethal injections.
The sedative, known commercially as Versed and commonly used as sedation for minor procedures, was adopted by Florida officials after the state reported dwindling supplies of pentobarbital, a barbiturate. The shortage was due to a decision by the drug's manufacturer to clamp down on sales for its use in executions, prison officials said.
After the sedative is administered, the prisoner receives a second drug that acts as a paralytic agent and the third drug stops the heart.
Last month, seven Florida death row inmates sued the state, arguing midazolam was not an anesthetic. But a judge dismissed their legal challenge, which claimed that the drug left inmates aware of their surroundings but unable to speak or move and in extreme pain in their final minutes.
In the Texas case, McCoskey was convicted of kidnapping a couple in 1991 in Houston, raping the woman and stabbing her fiancé to death.
Lawyers for McCoskey, 49, have told media they are not planning any last-minute appeals.
The victims were Michael Dwyer, 20, and his 19-year-old fiancée, whose name was not listed on the Texas Department of Criminal Justice's website because she was a rape victim. She survived the assault and identified McCoskey in a police line-up.
Texas has executed 506 prisoners since the reinstatement of capital punishment by the U.S. Supreme Court in 1976, the most of any U.S. state.
(Writing by Kevin Gray; Editing by Lisa Shumaker)