Well, he can't defend himself now.
Possibly, the hopelessness of American jurisdiction, where you need shedloads of money to mount an effective defense, and maybe he didn't have it, or couldn't raise it.
Guilty or innocent? We'll never know.
If a prisoner is executed in the US, my understanding is that the evidence is automatically destroyed*. Guess the same (suicide?) applies to this bloke.
*Corrections greatfully received, BTW.


