Honestly ! You should read The Co-Ed Killer by Margaret Cheney, it’s about ed kemper who is the ultimate ‘i did it cos of my mother’ serial killer and Cheney isnt having any of it. She goes into lots of detail on the inconsistencies in kemper’s confessions regarding his mother/childhood and how convenient it is for him to offload all of his guilt and blame onto his mother who isn’t alive (because he killed her) to defend herself or tell her side of the story. I really loved Cheney’s book a lot. She also introduced a really interesting theory about why serial killing in general spiked so much in 70s and poses that men with an existing propensity for misogynistic violence were ‘triggered’ by womens’ growing social and sexual liberation, and that by killing women they deemed to be ‘too free’ they were punishing the individual woman, but also scaring women as a whole into declining to exercise their growing social mobility. Idk how much I think that’s like 100% true but it was still very interesting to read about, I love true crime literature by women. The book is really hard to get hold of a physical copy because it went out of print in the early 80s (I got mine in a charity shop years ago) but there is a kindle edition available and im sure you could find a PDF somewhere too.