Last October, two people were arrested in Winnipeg after a 30-year-old woman complained that she was given a substance at a couple's home in April that made her unconscious.
She said when she woke up, she discovered that she had been sexually assaulted and contacted police.
Winnipeg police say three other women have come forward with similar allegations that go back as far as 2000.
"The three victims individually and on separate occasions had attended the accuseds' residence," police spokesman Const. Eric Hofley said Thursday.
"During these incidents, two were administered a stupefying substance and at least one of the victims was rendered unconscious. During these incidents all three of the victims were sexually assaulted."
Richard Gordon, 45, and Jackie Burgoyne, 34, were arrested Wednesday and face multiple charges of sexual assault, forcible confinement and administering a stupefying substance to overcome resistance to sexual assault.
They have been released from custody and are to appear in court March 6.
In October, Gordon was charged with sexual assault and administering a noxious substance with intent to endanger life or cause bodily harm. Burgoyne was charged with sexual assault.
A Manitoba Justice official declined comment on their status.
Sheriffs in Manitoba provide court security, serve and deliver court documents, escort jail inmates and perform other duties.
The Winnipeg Free Press says Gordon and Burgoyne filed a civil lawsuit over their appearance with a woman in a pornographic video called "Grey Cup Blond" that was available on the Internet in 2006.
The common-law couple was suspended for a few months but got their sheriff jobs back in 2007.
In their lawsuit, the couple said they did not consent to the video becoming public. A judge ordered an amateur porn star named Oshean de St. Claire de Guise to remove the video from her website.
The Free Press reported that Oshean and her husband produced consent forms signed by the couple to participate in adult photo and video production for commercial purposes.
It was not immediately clear if the civil lawsuit has been resolved.