Do you think that Beah should be held accountable for the murders that he committed while serving in the army?

When answering this, you really need to put the situation into context. Ishmael is a mere child when he was forced into the army. I think that "force" is the operative word here. Once he entered the camp he was indoctrinated into a mindset. He was also pumped up full of drugs that his own reality was muddled at best. The country was in chaos; there was nowhere to go. So no, Ishmael cannot be held responsible. Unlike traditional war criminals, Beah was a boy. He was forced by adults to fight or be killed himself. The mind of a child is very different than the mind of an adult. In the end Beah adapted to his environment. Although abused beyond belief, Ishmael was a survivor. Most of the people he killed were trying to kill him. As a mere boy in a jungle hopped up on cocaine and gunpowder, what is a child supposed to do?