It was hypothesized that when her heart stopped and oxygen levels fell, the DMSO in her system turned into dimethyl sulfone.

Ramirez was taking dimethyl sulfoxide (DMSO) for pain, a home remedy that is a gel-like solvent.

On the evening of February 19, 1994, at the Riverside General Hospital in California, 31-year-old Gloria Ramirez was rushed into the emergency room. She was suffering from severe complications related to late-stage cervical cancer. She was confused, having trouble breathing, and her heart was beating very rapidly.

What happened next was a massive investigation to find the "toxic" substance. Initial theories ranged from infectious disease to chemical weapons, but all tests on the surrounding air and hospital equipment were negative.

Later, electrical shocks from defibrillation could have converted this into dimethyl sulfate, a highly toxic nerve gas.

One nurse, Susan Kane, fainted after smelling the blood. Another nurse experienced a burning sensation in her face and arms. A respiratory therapist became dizzy, and within a few minutes, nearly a dozen medical staff members began to fall ill, with many passing out or experiencing muscle spasms.

Forensic scientists and investigators later proposed a theory to explain the incident: