CALGARY - A Calgary psychiatrist who frequently provided expert opinions in court now faces 21 charges of sexual assault, most of which allegedly took place during court-ordered visits.

Dr. Aubrey Levin, 71, was first arrested and charged in Calgary in March after allegations that he repeatedly assaulted a 36-year-old patient.

"Following this charge, the sex crimes unit was approached by numerous people alleging they, too, had been sexually assaulted by Dr. Levin during counselling sessions or court-ordered visits," Calgary Police Insp. Steve Barlow said Friday.

"These assaults allegedly occurred at Levin's office or examination room."

Levin has been charged with 20 additional counts of sexual assault involving 20 other patients, all men.

Barlow said most of the assaults allegedly took place during court-ordered visits, although he couldn't give an exact number. Some of the complaints came from people who are currently incarcerated.

Alberta Justice has been reviewing all criminal cases in which Levin offered testimony to ensure there were no miscarriages of justice.

Spokesman David Dear said Levin's work in 17 cases now before the courts has already been revisited by other psychiatrists, or will be. Senior prosecutors are reviewing 21 other closed cases in which Levin gave his opinion.

"There are a number of factors to consider, and certainly one of the important ones is if Dr. Levin's work played a significant part in the case in any way, and then to take additional steps from there depending on how that's assessed," he said.

Dear said Levin most commonly prepared reports to help inform the court's decisions after a person had already been convicted. "His work would normally have been psychiatric reports to help the court determine an appropriate sentence."

Levin's licence to practise medicine was temporarily suspended by the College of Physicians and Surgeons when the original charge was laid, said spokeswoman Kelly Eby.

She couldn't confirm whether any patients had registered complaints against the doctor, saying those would be confidential unless there were a disciplinary hearing.

Barlow said he couldn't confirm whether audio or video recordings were made of the court-ordered sessions, saying such information forms part of the investigation.

Police said Levin is free on bail on condition that he remain in Canada, has no contact with the alleged victims and does not practise medicine.

Levin is no stranger to controversy over his work as a psychiatrist. He faced heated accusations about his time as a military psychiatrist during apartheid in South Africa, where he earned his degree in 1963.

He was a psychiatrist at a military hospital in the 1970s where aversion therapy through electric shocks was allegedly used in an attempt to change the sexuality of gay soldiers. Levin is mentioned in a report entitled the aVersion Project that attempted to shed light on abuses of gays and lesbians in the military by health workers.

Media coverage of the South African Truth and Reconciliation Commission said that Levin was named by a Health and Human Rights Project submission as being a key figure in the abuse of gay men in the military. It acknowledges that the submission was based on anecdotal reports.

Levin has denied that he abused any patients under his care, and argued the submission was based on a distortion of the facts, according to an article in the South African Medical Journal.

A 2003 report compiled by the Gay and Lesbian Archive and the South African History Archive attempted to put together a history of Levin's work as a psychiatrist any role he may have played related to gay and lesbian soldiers.

According to the report, Levin confirmed in a letter to the Truth and Reconciliation Committee that he had practised aversion therapy, but said that it was an accepted form of therapy at the time for patients who did not accept their homosexuality.

He has denied in media reports that he ever administered shock therapy, and said the aversion therapy consisted of applying very slight discomfort to the arm of consenting patients.

The Truth and Reconciliation Commission was set up by the country's government to help deal with the violence and human rights abuses experienced under apartheid.

The report says two complaints were filed against Levin to what was then the South African Medical and Dental Council.

It says in one case the father of the complainant said the "consultation had degenerated into an overt homosexual advance."

It says in the other case the complainant said Levin inquired about his sexuality and implied to his mother that he was gay. Levin apparently received an anonymous retraction of the second complaint, which he forwarded to the council.

Both complaints were dismissed.

The report says Levin was a National Party member at the time and that most professional bodies during apartheid were weighted towards the party, meaning "he may be perceived to have received a somewhat sympathetic hearing."

After coming to Canada, Levin served briefly as regional director of the federal Psychiatric Centre Saskatoon as an employee of Correctional Service Canada and has been a licensed psychiatrist in Alberta since 1998.

His defence lawyer, Alain Hepner, has said Levin planned to fight the original sexual assault allegations in court. He said that he expected the case to be long and complicated because Levin has been practising for more than 40 years.

Hepner could not be reached for comment Friday on the most recent charges.