apparently he was balls deep into the occult, he did a bunch of weird rituals with L Ron Hubbard with the direction of Aleister Crowley called Babalon Working

they tired to summon a woman (divine feminine called Babalon) to partake in sex magik to conceive some bastard demon child. they met a woman who fit the bill and performed some rituals but failed ultimately

L Ron ended up running away with Jacks wife and stealing a bunch money off him. (needed some funds to start scientology i guess)

Then a couple years later Jack blew himself up in some weird lab accident.