Arizona Department of Corrections, Associated Press
In this undated photo provided by the Arizona Department of Corrections shows Thomas Arnold Kemp, a death-row inmate. Kemp convicted of killing a Tucson college student after robbing him of $200 is set to be executed on Wednesday, April 25, 2012, in what would be the third execution in Arizona this year. Kemp was sentenced to death for kidnapping 25-year-old Hector Soto Juarez from outside his Tucson apartment on July 11, 1992, and robbing him before taking him into a desert area near Marana, forcing him to undress and shooting him twice in the head.

FLORENCE, Ariz. — The attorney for an Arizona death-row inmate executed Wednesday says he is "very disturbed" after seeing his client shake for several seconds after receiving his lethal injection, and he wants to find out if the man experienced any unnecessary pain.

Sixty-three-year-old Thomas Arnold Kemp's one-drug execution took place at about 10 a.m. at the state prison in Florence.

As it began, Kemp's eyes closed and his body visibly shook for several seconds before he went quiet and appeared to fall asleep with a few deep breaths.

His attorney, Tim Gabrielsen, tells The Associated Press he is considering what action can be taken to determine if Kemp was in pain, including an autopsy by an independent pathologist.

Arizona Department of Corrections spokesman Bill Lamoreaux says Kemp was offered a mild sedative before the execution but declined it. He also says Kemp was given blankets after expressing he was "a little chilly."