My input is this-
He was probably if not definitely not a pleasure killer or a masochist (Someone who gets pleasure from causing pain). I have come to this conclusion because unlike pleasure killers such as Ted Bundy and John Wayne Gacy he stopped after only five murders. In the case of the two other killers, they killed many due to lust and the killings where often violent due to the killer getting exited during the murder. This would not have been possible for Jack as the speed and precision at which he committed his murders would not have been possible if he had all the excitement at the killing as he would not have been able to cut as cleanly and quickly as he did. There was also no evidence of sexual tampering with the bodies, which is usually the case with most pleasure serial killers or masochists.
