A man convicted of the 1992 murders of three people has been put to death by lethal injection in Florida on Thursday in the 11th execution in the southern US state this year.

Curtis Windom, 59, was sentenced to death for killing his girlfriend Valerie Davis, her mother Mary Lubin, and Johnnie Lee, a man who allegedly owed him a gambling debt. The execution was carried out at 6:17 pm (2217 GMT) at the Florida State Prison, and his last words were unintelligible, according to US media witnesses.