Following the death of co-founder Bonnie Nettles, Marshall Applewhite Jr. had to come up with a new theology from physical space travel to the belief that they must "shed their human vehicles" through suicide to ascend. The group maintained extreme control over members through check partners, enforced androgyny—including surgical castrations—and intense indoctrination involving sci-fi media like Star Trek. In March 1997, believing a spacecraft was trailing the Hale-Bopp comet, 39 members committed ritual suicide in a California mansion wearing matching uniforms and Nike sneakers.

Resources:

https://time.com/archive/6730591/imprisoned-by-his-own-passions-marshall-herff-applewhite/

Heaven’s Gate: The Cult of Cults on HBO

https://facilitatingu.com/2014/07/20th-anniversary-of-my-heavens-gate-departure/

https://en.wikipedia.org/wiki/Heaven%27s_Gate_(religious_group)

https://www.heavensgate.com/

https://www.history.com/this-day-in-history/march-26/heavens-gate-cult-members-found-dead