Pre-mediation does not mean you understand the consequences of your behavior. It doesn't mean you don't have serious problems with reality testing (here, I'm surprised that no one has brought up the idea of Folie a Deux as a possibility here). The ability to execute the crime in a planful fashion doesn't equal culpability. I don't know how much to write about it but UGH. I used to do forensic evaluations and fuck, these cases, along with a broad narrative around mass incarceration, make it a lot harder to actually do the due diligence required to give a fair disposition because everything becomes politicized. There is an advantage to having experts look at these cases. Everything shouldn't be tried in the court of public opinion.