Dow was found dead on Tuesday inside Headingley Correctional Institute, where he was serving a 16-month sentence for sexual assault and simple assault, his lawyer, Crystal Antila, confirmed to CBC News.
The cause of death is currently not known. An autopsy will take place on Wednesday, said Dr. Thambirajah Balachandra, the province's chief medical examiner.
RCMP spokesperson Sgt. Line Karpish confirmed that officers from the Headingley detachment were called to the provincial jail at 10:30 a.m., but she did not release any other details.
In an email, Antila said she was shocked and saddened by news of Dow's death.
Antila said she had not spoken to her client recently, so she was not aware of "any specific concerns that he may have had as of late at the institution."
Sex assaults happened at photo shoots
Dow was 58 years old when he was sentenced in September to 18 months in jail on 11 counts of sexual assault. With credit received for two months he had spent in custody, he had 16 months left in his sentence.
Dow pleaded guilty to the sexual assault charges, as well as one count of simple assault, that date back to a five-year period between 2000 and 2005, when he was running the Ricoco International modelling agency as a side business.
Court heard that almost all of the sexual assaults took place at photo shoots and involved young women between the ages of 17 and 23 years old.
The assaults involved inappropriate and unwanted sexual touching, court was told.
Dow operated the business while continuing to serve as a police officer. He retired from the Winnipeg Police Service in 2007, following an 18-year career.
In a separate trial last year, a jury found Dow not guilty of sexually assaulting a female modelling client during a photo shoot at his home in 2000.