The Federal Bureau of Investigation is now leading an investigation into a device which may be responsible for spreading a deadly cancer.

Morcellators are medical power tools used to perform hysterectomies, procedures that remove the uterus to treat uterine fibroids. Basically, morcellators break the tumors up into smaller pieces, so they can be more easily excised.

However, in as many as one in 350 cases, cancer is sometimes hidden in fibroids. When the morcellators cut the fibroids up to remove them, surgeons may inadvertently leave some pieces behind. If these remnants contain cancerous cells, they become free to spread the deadly disease throughout the rest of the patient’s body.

“The FDA has no idea how many women had cancer spread by being treated with this device,” said ABC News Chief Medical Editor Dr. Richard Besser. “But the idea that anyone was harmed is very concerning.”

Johnson and Johnson, which was the top manufacturer of power morcellators, was alerted to the potential risk back in 2006, but did nothing until July of last year, after the U.S. Food and Drug Administration issued warnings back in November.

Now, the FBI is investigating Johnson and Johnson, to find out what they knew and when. The company told ABC News that the FBI has not yet contacted them, but the FBI has been in touch with some victims of botched morcellations.

According to the Wall Street Journal, the FBI has contacted three people over the past several months about the surgical device, including Dr. Amy Reed. The anesthesiologist underwent a hysterectomy via morcellation to have her fibroids removed in 2013 — only to find out that the device had worsened her cancer. Now, she and her husband campaign to ban morcellators in an effort to save the lives of women everywhere.

The FBI has also spoken with Sarah Robinsin, according to the WSJ. The physician assistant has already testified at an FDA hearing on the device, and has also created a list of women and families affected by morcellation.

She has sent the list to the FBI, which names 386 people, including herself.