 Guiteau was indicted on October 14 , 1881 , for the murder of the President . In a chaotic trial in which Guiteau often interrupted and argued , and in which his counsel used the insanity defense , the jury found him guilty on January 5 , 1882 , and he was sentenced to death by hanging . Guiteau might have had syphilis , a disease that causes physiological mental impairment . He was executed on June 30 , 1882 . 
