Calgary Serial Rape Suspect Richard Mantha Found Guilty on Six Charges, Cleared on Majority
Richard Robert Mantha, a 62-year-old resident of Rocky View County east of Calgary, has been found guilty on six charges, including sexual assault, while being acquitted on the majority of the 20 charges he faced. Justice Judith Shriar delivered the verdict on April 7, 2026, following a trial that began in January 2024 and experienced multiple delays.
Verdict Details and Judicial Findings
Justice Shriar convicted Mantha of sexually assaulting three of the seven women he was alleged to have abused. However, she agreed with defence lawyer Justin Dean that much of the testimony from the alleged victims, primarily vulnerable women, was unreliable, leading to acquittals on most charges. The judge noted that while Mantha provided drugs such as fentanyl, methamphetamine, and crack cocaine to most of his alleged victims, she was not sufficiently convinced that he administered these noxious substances with intent to endanger lives or cause bodily harm in most cases.
Mantha was convicted on one charge of administering a noxious substance, but Justice Shriar found it was only to "aggrieve or annoy" the victim, not to cause serious harm. She emphasized that an accused cannot be found to have administered a noxious substance if the complainant voluntarily consumes it.
Case Background and Trial Developments
Mantha was arrested on April 6, 2023, after Calgary police, with RCMP assistance, conducted an extensive search of a rural property east of Calgary where he was renting a Quonset hut. The search, which lasted days and included police cadaver dogs, did not uncover any bodies. The trial faced several delays, including a stroke suffered by Mantha in May 2024 that left him unable to verbally communicate.
During final submissions, Crown prosecutor Dominique Mathurin conceded acquittal on two of the seven alleged sexual assault victims, including one who died before testifying. Mathurin's application to enter that woman's police statement as evidence was denied by the judge. While Mantha was cleared of sexually assaulting the second woman for whom the Crown conceded evidence fell short, he was found guilty of threatening that complainant.
Specific Assault Details and Upcoming Sentencing
Justice Shriar found that one of the sexual assaults committed by Mantha at the Quonset hut off Vale View Road involved him choking his victim. She also ruled that Mantha physically assaulted the woman with a weapon during the sexual attack by striking her with her cell phone, but noted that a knife nearby during the assault was not used to commit the crime. He was found to have sexually assaulted two other women, with one acquitted on drugging charges and the other found to have been drugged to "aggrieve or annoy" her.
Mantha's case is scheduled to return to court for Dean and Mathurin to schedule a sentencing hearing before Justice Shriar. He remains in custody pending sentencing, with the proceedings highlighting the complexities of prosecuting cases involving vulnerable victims and substance-related allegations.
