Georgia executed a convicted killer on Tuesday despite the objections of his lawyers who argued he was mentally disabled and should have been spared the death penalty, the state's top lawyer said.

Warren Lee Hill, 54, was pronounced dead by lethal injection at 7:55 p.m. (0055 GMT Wednesday), after the U.S. Supreme Court denied a request to put his execution on hold, Georgia Attorney General Sam Olens said in a statement.

The Georgia Board of Pardons and Paroles refused on Tuesday to stop the execution, as did the state Supreme Court last week.

Hill was condemned for beating fellow inmate Joseph Handspike to death in August 1990. At the time, Hill was serving a life sentence for the 1985 shooting death of his 18-year-old girlfriend, Myra Wright.

Five thousand people signed a petition seeking to spare his life and it was presented to the state parole board, his lawyers said.

Hill's supporters included former President Jimmy Carter and his wife, Rosalynn, the American Bar Association, the American Civil Liberties Union, the European Union and the Georgia chapter of the NAACP, according to his attorneys.

A strong section voiced its feeling that Hill would have been spared if he was not black. 

"This execution is an abomination," Hill's attorney, Brian Kammer, said in a statement. "The memory of Mr. Hill's illegal execution will live on as a moral stain on the people of this State and on the courts that allowed this to happen."