The Discovery Channel program linked below will be shown again on Wednesday at 6PM EDT. It discusses MK Ultra and even runs an experiment on mind control. If the experiment can be taken at face value it shows it would be possible to brainwash someone into committing a murder.

It also suggests Thomas Crooks might have been operating under mind control.

https://go.discovery.com/video/conspiracies-coverups-discovery-atve-us/mind-controlled-assassin

https://www.imdb.com/title/tt41370247/?ref_=ttep_eps_tp