In the fourth episode, Hacker and Peace are escorting Tachihara to a safehouse when they are intercepted by the berserk Hunter, Lucifer. Lucifer rapes and kills Peace while forcing Hacker to watch. Hacker tries to shoot Lucifer but Lucifer uses her telekinesis to destroy Hacker's gun.
A short while later, Angel arrives on the highway and encounters Hacker. Without saying anything, Hacker holds a grenade up and the pin slides out seemingly of its own volition, though it is of course Lucifer using her psychic powers again to control Hacker's body and the grenade pin. Angel yells at Hacker to get rid of the grenade, but it explodes in his hand. When the dust settles, Lucifer stands where Hacker was stood, holding his head in her hand.
It is possible that Lucifer could have killed Hacker before Angel arrived, hence why he did not speak before blowing himself up. Lucifer may have just been controlling his lifeless body like a puppet, though this is unconfirmed.