Unsealed FBI documents show traces of a chemical warfare agent were inside an Oklahoma home.

The suspect, Phillip Heath, was arrested in January after police responded to his Lawton apartment to investigate a domestic disturbance.

Police say it was a plea for help that led to the discovery of a chemical that can inflict immediate pain and even death.

The 911 call led FBI agents to Heath's apartment. What was found inside the apartment explains the commotion surrounding it back in January.

Caller: He’s Threatening me!

Dispatcher: What’s he saying?

Caller: He’s saying he has a gun and he’s going to shoot me.

“It took the chemists actually going in there to figure out exactly what they had, and so again they were preparing for something that could be an inhalation hazard or skin absorption hazard,” said Oklahoma City Fire Departments District Chief of Safety Clint Greenwood.

Over the next 48 hours expert chemists in hazmat suits carefully inventoried the apartment.

“That’s where you see the extra measures making sure they wear the right protective clothing, the chemical protective clothing,” said Greenwood.

An exhaustive search uncovered a treasure trove of contraband including glass laboratory equipment and containers consistent with the manufacturing of methamphetamine.

The search also uncovered a large quantity of unmarked containers filled with various liquids and powders—all precursors for homemade explosives.

Further testing later uncovered Phosgene Oxime or CX.

“It is corrosive you could start seeing blisters and things like that, so if it does that to the outside skin imagine if you're breathing it in what it would do to your lungs,” said Greenwood.

Heath has a prior conviction for manufacturing explosives.