Lieutenant Peter Chew and HAZMAT Team Delta are friends of HAZMAT Team Bravo, and Chew is a good friend of Ethan Cole. He is the last member of Delta to die after they are ambushed by Black Ops soldiers. He slides down a rigged elevator shaft which has a bomb attached to the railing and is consumed by a mutant leaper at the bottom.
Before HAZMAT Team Bravo came to Area 51, Delta was sent to investigate the mutagen disturbance. It came to an unknown position and all the officers except for Chew was killed, along with the survivors he fled. The team came to find the Weapons Range.
Ethan Cole learned that HAZMAT Team Delta was still alive because of the live transmission by Lieutenant Chew. He then opened a door to find a vast large hall with mutants surrounding Delta and Chew. He jumped down to Delta and Marco Ferri was happy to see a familiar face. After first wave of mutants Ethan was sent by Chew to the armory.
Ethan and Chew got on the turrets after Ethan had retrieved the plasma shells blasting every mutant in sight. Marco and an unknown Delta teammate went on the turrets to cover them getting explosives. Chew guarded the entrance to the second armory.
After Ethan passed the explosives to Chew, he sends Ethan to enter the left turret then shoot and detonate the explosives. The explosion opens a hole in the wall from which mutants come in and then mutwnts come from both balconies on top. When the team kills all enemies with the help of Ethan on turret a cutscene opens. It reveals thaat the beast that killed Delta team's first members as well as Chrispy and Ramirez is a Theta.
All the HAZMAT team are dead except Ethan and Chew. The last cutscene is the last moments of Ethan's humanity and the last minutes of Chew's life. A scene shows Black Ops soldiers arming bomb as they placed detonating bomb on the maintenance elevator to kill the HAZMAT team survivors.
Ethan helps Chew get up and asks him about the creature that appeared. Ethan said he thinks it is the one to kill his team. They walk to the maintenance elevator, and they wonder who created it. It appears to be a launch tube. Chew calls Major Bridges informing him of the death of his teammates, as well as the companion of his: Ethan Cole. That's when the bomb explodes knocks out Chew out of the launch tube and Ethan into an emergency chute. With this the final cutscene opens up revealing the reason of mutation of Ethan Cole. The mutant kills Chew biting him dead then bites Cole poisoning his body. He turns into a mutant, and then we see the flying body of Chew telling Ethan what to do.