I doubt anyone has died at Hannibal's hands in the three years he's been imprisoned. For one thing, he and Alana discuss his dozen, or baker's dozen, of murder convictions. Surely it would come up if he'd killed someone in the asylum.
For another, I think it makes sense if Hannibal only starts killing people while imprisoned once the storyline of Red Dragon plays out and
His whole attitude to his situation changes after that point, I think.
There's a typo in the first line of the crime scene report Will looks at - I think from memory is says "lai" instead of "lay".