NEW YORK -- A surgical device used on millions of women may be responsible for spreading a deadly cancer.
The FBI office in Newark, New Jersey is leading the investigation into the device, which is made by Johnson and Johnson and other companies.
The laparoscopic power morcellator was once used on tens of thousands of women every year.
It's used to treat fibroids, or benign uterine tumors which affect up to half of women under 50, by breaking the fibroids into pieces so they can be more easily removed.
But in as many as one in 350 cases, cancer is hidden in that fibroid and can be inadvertently spread by the device.
ABC News Chief Medical Editor Dr. Richard Besser explains, The FDA has no idea how many women had cancer spread by being treated with this device. But the idea that anyone was harmed is very concerning."
Johnson & Johnson tells ABC News that they have not been contacted by the FBI. But some of the people who say they are victims have been contacted.
Dr. Amy Reed says it happened to her.
The anesthesiologist says she was checked for cancer before a hysterectomy last fall.
The results came back negative. But then after the morcellation, doctors did find a rare form of cancer.
Dr. Reed tells us, "At no point in time did anyone ever say, 'Well you know because you had it morcellated, that worsens your prognosis.' That's something we discovered on our own."
Johnson & Johnson was the top manufacturer of the device. The FBI is now looking into what they knew and when.
The medical supply powerhouse was first alerted to the possible risk in 2006 by a pathologist, and didn't pull the device off the market until July of last year - doing so voluntarily "due to the continued uncertainty," the company said, adding, "To date, we are the only manufacturer to proactively take this action."
This investigation comes after the FDA warned back in November that morcellators should not be used on most women.
Now many hospitals across the country have stopped or cut back their use of the device.