No, if it is known there is a medical issue causing the behavior the person is not held accountable for the crime. Can be tricky with a brain tumor though and learning about it before death (doing an autopsy and finding the tumor would not help a person much :-)

There have been cases where people have murdered their spouse while asleep Homicidal sleepwalking - Wikipedia, the free encyclopedia

Interesting discussion of what happens/can cause a tumor/murder combination: http://brainmind.com/Case5.html

The Atlantic magazine article, "The Brain on Trial": http://www.theatlantic.com/magazine/...-trial/308520/