The scientist, whose name is Larry, leads you toward Subject Zero's cell.
"And remember that the only way to kill them is to shoot them through their heads. That's where the Reanimators are and killing the hosts doesn't ease their control over them," the scientist advises you.
"How do the Reanimators still get blood from their hosts despite the fact that the hosts are dead?"
"When the Reanimators take command over the body, they can keep all the body parts intact and can have the heart continue to function after the host is dead."
"What about Subject Zero? A bullet to the brain for him as well?"
"I don't know."
"What do you mean, you don't know?"
"Look, Subject Zero has suffered a massive mutation. We don't even know if the brain is in the head anymore. His original Reanimator has completely altered his anatomy. The only way to make sure that Subject Zero dies is to either annihilate every cell in his body or use the bionic weapon. Only one of those ensures a confrontation with the monster."
"You're right. Going for the weapon is our best bet."
You reach Subject Zero's cell with minimum trouble, having only to deal with a few infected people.