The Toolbox Killers

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Lawrence Bittaker and Roy Norris were a serial killing duo active in Southern California in 1979, who abducted teenage women in a van, raping, torturing, and then killing them. The pair claimed five lives during their crime spree, which isn't a lot considering how many some killers have claimed, but a lot of people involved in this case were purportedly disturbed by the level of brutality on display. Norris and Bittaker had made a 17 minute tape of one of their killings, and when it was played during the trial, people walked out of the courtroom, openly wept, or both. Allegedly the tape is used to train FBI Agents and desensitize them to some of the crazy shit they might encounter on the job, which is hardcore if true. Only transcripts of the tape exist to the public, you can find it here (NSFW obv).

Aside from the superficial similarity to Eric and Dylan in that they were also a duo who killed people, this little tidbit about Bittaker's life stood out to me:
"Bittaker's adoptive father worked in the aviation industry, which required the family to frequently move around the United States throughout his childhood."

Just something that makes ya think.