TORONTO - A surgeon from Windsor, Ont., who performed two unnecessary mastectomies won't be disciplined by the province's medical regulatory college.

Dr. Barbara Heartwell became the subject of several investigations after it was revealed she mistakenly removed the healthy breasts of two women at Hotel-Dieu Grace Hospital.

The College of Physicians and Surgeons of Ontario launched investigations into Heartwell and pathologist Dr. Olive Williams, and the college's spokeswoman says the Heartwell investigation has been completed.

Kathryn Clarke says the outcome of the investigation can't be publicly disclosed, but the college did not refer the matter to its discipline committee.

In general, investigation outcomes that can't be made public include deciding no further action is necessary, cautioning the physician about some aspect of their conduct, care or treatment, or requiring the physician to participate in an educational program.

A provincial report into pathology errors appeared to clear Heartwell, but uncovered "significant concerns" with Williams' work.

Hotel-Dieu Grace Hospital has restored full privileges to Heartwell, but not Williams.

In November 2009, Laurie Johnston of Leamington, Ont., had a mastectomy performed by Heartwell, who admitted she misread the results of a needle biopsy that found Johnston did not have cancer.

Janice Laporte, whose breast was removed by Heartwell in September 2001, was told a week after her surgery that she didn't have cancer.