Sunday, September 11, 1921, was a day of preparing for the next evening’s Grand Jury session. The preparation and ongoing investigations were overseen by Duncan Matheson, San Francisco’s long-serving Captain of Detectives. Unlike his subordinates, he was cast from a different mold and hardly the Irish American stereotype of Dashiell Hammett’s novels.

Born in 1865 in Nova Scotia, Matheson was of Scottish ancestry. As a young man, he emigrated to the United States and began working as laborer for the Southern Pacific Railroad. By 1900, he had married and was roadmaster for the Mojave District and in charge of track maintenance through the California desert. Then, in 1901, Matheson joined the San Francisco Police Department at the relatively advanced age of thirty-six and began working as a patrolman along the Mission Street wharves, where he was feared for the way he would swing a nightstick in breaking up fights and the like. His exploits were often newsworthy, including a time he crashed through a skylight while jumping from one building to another in pursuit of a gang of juveniles.

Over the first decade of the new century, Matheson became a real-life Untouchable—his resemblance to Sean Connery’s Frank Malone, is striking—rising in rank from sergeant to lieutenant by 1911. That year Matheson was put in charge of policing Chinatown, where he had been given the task of curbing its illegal gambling, lotteries, narcotics, and notorious tongs (gangs). Perhaps because the “Chinese were more afraid of him” than they were of the police chief, Matheson was promoted to Chief of Detectives by 1916.

Matheson gained notoriety for his role in the investigation that led to the arrest and conviction of the radical labor activist Tom Mooney for the Preparedness Day Bombing of July 22, 1916, along San Francisco’s Market Street. American socialists organized numerous protest rallies across the country in support of Mooney and Matheson is still recognized in historical accounts for the part he played in allegedly framing him.

One can imagine Matheson seeing himself as cut from the same cloth as the cowboys and others who settled the west. He was a skilled horseman, sometimes saddling up to lead a posse into the hill country around San Francisco in search of a suspect. And as the father of a teenage daughter, was protective and sympathetic to issues that would impact her as the 1910s came to a close and women’s suffrage and Prohibition loomed.

A nondrinker and public speaker, Matheson once spoke before the Women’s Christian Temperance Union (WCTU) about how he intended to enforce the new Volstead Act. He spoke to the Housewives League on the need to protect girls and young women—from themselves, for, as he noted, seventy percent of all the juvenile cases he handled involved girls who had gone “bad.” In early 1921, when the state tried to reduce funding for the State Home for Delinquent Women, Matheson spoke against the defunding given the rise in girls and young women involved in criminal activities.

As much as Matheson took a grim view of radicals setting off bombs in his city, he also shut down at least two high-profile abortionists, Dr. Ephram Northcott in 1919 for the botched abortion and death of an army nurse, and the infamous Dr. Galen Hickok in 1920, whose victims remains were buried on the grounds of his so-called “castle of mystery” overlooking Salada Beach. In October 1920, Matheson and his detectives investigated the murder of a so-called “nightlife habitué” and prostitute Ruby Allen. She had checked into the Knickerbocker Hotel and was later found dead, bound and gagged, the victim of an apparent robbery by one of her johns. Although Matheson claimed he knew who the killer was, no one was brought to trial.

Matheson, too, took a prominent role in the investigation of the brutal gang rape of two girls in a shack on Howard Street by a gang of juveniles in November 1920 that became a cause célèbre for San Francisco’s women’s groups and clubs that packed the courtroom to see Arbuckle brought to justice for what many of them believed was a rape. Lastly, in April 1921, Matheson busted a white slavery ring and included two men charged with conducting orgies with three young girls and grooming them to appear in pornography films and photography.

Having learned firsthand what some men were capable of doing to women, Matheson was primed to act when he was told what happened to Virginia Rappe at Arbuckle’s Labor Day party and saw what was left of this beautiful woman in the city morgue.