Archeotech cortex implants are worth killing over. When Tristen Hob joined the Adeptus Mechanicus, he quickly learned this fact. Tristen’s mentor and friend Nicolai helped him perfect his form by finding a electro-graft and cyber-mantle, so when Nicolai arrived with a cortex implant Tristen thought nothing of it.
Still new to the technology spirits, Tristen simply believed the brain implant did it’s job well as entire new avenues of math and science become child’s play for him. He never suspected anything as members of the Mechanicus questioned him about Nicolai’s activities and recent cybernetic adjustments.
Finally the truth was revealed. Nicolai stole the technology and used Tristen to hide it until suspicion died out. Then he would kill Tristen, extract the implant and use it himself. The inner circle of the Mechanicus dealt with Nicolai severely, ensuring his betrayal and theft would be punished for years before death was granted.
However, this still left the implant in Tristen’s brain. Practically a holy relic, they could not allow him to waste it, when someone much more deserving could benefit from this ancient holy tech. The fact that it couldn’t be extracted without killing Tristen was regrettable, but necessary. However, Tristen had other plans.
Erasing information and killing certain people, Tristen managed to escape the clutches of the Mechanicus and eventually ended up on a Rogue Trader ship. The traders put up with his lack of diplomacy and people skills since his implant made him one of the finest techs in the universe. Tristen knows there are a few people who are still hunting him, and they’ve taken advantage of the mess Tristen left behind to eliminate the Archeotech Implant from all records, presumably to steal the artifact for themselves.