Gardner was strapped into a chair where a team of five marksmen aimed their guns at the white target pinned to his chest.
Gardner was convicted of the murder of an attorney in 1985 while he was trying to flee a Utah courthouse where he was to be summoned for another murder case.
Lethal injection is the default execution method in Utah, since 2004. Gardner was the one still allowed to choose this execution method as he was sentenced before the law changed. Gardner, when given an option, chose firing execution. He said his lawyer that he preferred it, not because he wanted the controversy surrounding the execution to draw attention to his execution or embarass the state.
Gardner was pronounced dead at 12:20 am. Gardner's family was present outside the prison when he was shot. Gardner had requested them not to see his execution.