[1][2] On June 9, 1975, Steinhauser was one of 15 people that were taken hostage by three inmates, Andy Bruce, Dwight Lucas and Claire Wilson, who were attempting a prison breakout.

[7] Steinhauser grew up in Lake Cowichan until age 5, when she moved with her family to Burton, British Columbia, a small town in the West Kootenays, where her parents had purchased a farm.

[4] The three inmates demanded several things, including medical examinations for Lucas and Bruce, access to hot and cold water in isolation cells, and restoration of recreation yard privileges for segregated prisoners.

[17] Soon after, a tactical squad of prison officers attempted to rescue the hostages and fired upon the hostage-takers, fatally shooting Steinhauser, who was being held as a human shield in front of Bruce.

[5][17] This was proven to be erroneous by the coroner's report, which stated that Steinhauser had received two bullet wounds and also had abrasions, bruising, and recent needle marks in both forearms.

"[11] Andy Bruce went on to allege that, after being shot twice in the jaw by a prison guard he identified as Albert Hollinger, Mary Steinhauser crawled in front him, where "she screamed, 'Don't shoot him.'"

Trudeau stated how "very sorry" he felt about Mary Steinhauser's death and he discussed the federal government's commitment to not letting the inmates escape: "To make sure these guys wouldn't get off with anything...we would hound them wherever they were.

"[5] In July 1976 a jury ruled that the shooting was not intentional and that the guards, including Hollinger, were acting under the belief that Steinhauser's life was actively being threatened by the inmates.