STARKE, Fla. — An Army combat veteran whose Gulf War experience triggered severe mental problems was executed Thursday evening in Florida for the 1998 shotgun slayings of his girlfriend and her three young children.

Jeffrey Hutchinson, 62, was pronounced dead at 8:15 p.m. following a lethal injection at Florida State Prison near Starke. He was the fourth person executed this year in Florida under death warrants signed by Gov. Ron DeSantis, with a fifth execution set for May 15.

Hutchinson had no last statement but appeared to be mumbling to himself as the procedure started just before 8 p.m. His legs shook sporadically and he seemed to have body spasms for several minutes, then was still. The process took a little more than 15 minutes.

The execution was carried out soon after the U.S. Supreme Court rejected a final appeal without comment.

Hutchinson had long claimed he was innocent and that two unknown assailants perpetrated the killings under a U.S. government conspiracy aimed at silencing his activism on claims including Gulf War illnesses.

— The Associated Press