Apparently did not philosophize enough about his plans of ransom and murder. You demand ransom while the victim is held hostage. You demand ransom or you will kill the victim. You release the victim after ransom is paid. Only if you don't get paid, you consider your options which include killing the victim.
It sucks to have a 70 I.Q., like him. Now he'll have to philosophize for years how he messed up.
An even worse plan of action when one has grown up with the victim and has known her for years.
Although this guy sounds stupid enough to do something like that.
I think I hate stupid criminality more than smart criminality.
Stupid impulse, lives destroyed for brief indulgence or nothing at all. No calculation, no imagination, just selfishness and waste.