On November 13, 1974, 28-year-old Karen Silkwood is killed in a car accident near Crescent, Oklahoma, north of Oklahoma City. Silkwood worked as a technician at a plutonium plant operated by the Kerr-McGee Corporation, and had been critical of the plant’s health and safety procedures.

In September, she had complained to the Atomic Energy Commission about unsafe conditions at the plant (a week before her death, plant monitors had found that she was contaminated with radioactivity herself), and the night she died, she was on her way to a meeting with a union representative and a reporter for The New York Times, reportedly with a folder full of documents that proved that Kerr-McGee was acting negligently when it came to worker safety at the plant. However, no such folder was found in the wreckage of her car, lending credence to the theory that someone had forced her off the road to prevent her from telling what she knew.

On the night of November 5, Silkwood was polishing plutonium pellets that would be used to make fuel rods for a “breeder reactor” nuclear-power plant. At about 6:30 P.M., an alpha detector mounted on her glove box (the piece of equipment that was supposed to protect her from exposure to radioactive materials) went off: According to the machine, her right arm was covered in plutonium. Further tests revealed that the plutonium had come from the inside of her gloves—that is, the part of her gloves that was only in contact with her hands, not the pellets. Plant doctors monitored her for the next few days, and what they found was quite unusual: Silkwood’s urine and feces samples were heavily contaminated with radioactivity, as was the apartment she shared with another plant worker, but no one could say why or how that “alpha activity” had gotten there. (In fact, measurements after her death indicated that Silkwood had ingested the plutonium somehow; again, no one could say how or why.)

After work on November 13, Silkwood went to a union meeting before heading home in her white Honda. Soon, police were summoned to the scene of an accident along Oklahoma’s State Highway 74: Silkwood had somehow crashed into a concrete culvert. She was dead by the time help arrived. An autopsy revealed that she had taken a large dose of Quaaludes before she died, which would likely have made her doze off at the wheel. However, an accident investigator found skid marks and a suspicious dent in the Honda’s rear bumper, indicating that a second car had forced Silkwood off the road.

Silkwood’s father sued Kerr-McGee, and the company eventually settled for $1.3 million, minus legal fees. Kerr-McGee closed its Crescent plant in 1979.