A man convicted of raping a woman and murdering her brother while the siblings were on a camping trip is to be executed in the US state of Florida on Thursday.

Loran Cole, 57, is to be put to death by lethal injection at 6:00 pm (2200 GMT) at the Florida State Prison in Raiford, the Florida Department of Corrections said.

Cole was sentenced to death in December 1995 for the February 1994 murder of an 18-year-old Florida State University student, who was on a camping trip with his sister in the Ocala National Forest.

Cole was also convicted of sexually assaulting the murder victim’s elder sister, who was tied to a tree but managed to escape the next day.

An accomplice, William Paul, was sentenced to life in prison.

Cole has appealed to the Supreme Court to delay his execution on the grounds he has Parkinson’s disease and the lethal injection “will very likely cause him needless pain and suffering.”

“Cole’s Parkinson’s symptoms will make it impossible for Florida to safely and humanely carry out his execution because his involuntary body movements will affect the placement of the intravenous lines necessary to carry out an execution by lethal injection,” his lawyers said in a court filing.

“There are two other feasible alternative methods to lethal injection — lethal gas and firing squad — that will significantly reduce the substantial risk of severe pain that Cole faces if executed,” they said.

There have been 12 executions in the United States this year.

The death penalty has been abolished in 23 US states, while six others — Arizona, California, Ohio, Oregon, Pennsylvania and Tennessee — have moratoriums in place.