This is part one of a two part series.

For lawmen in the days of the frontier, the wide distances posed special problems as outlaws could easily disappear into the emptiness. As a result, a number of famous law enforcement officials stepped forward to counter that with as much determination and stubborn resilience as the harsh countryside. One of the most innovative was Charlie Siringo, a Texas native who caught more than 100 suspects in his career and brought him into contact with some of the most famous names of the Old West.

He was born Charles Angelo Siringo in Matagorda County in 1855. His parents were immigrants, his mother from Ireland and his father from Italy. Siringo’s father died when he was only a year old, and his mother struggled to raise him and his older sister. His education was sporadic, and he quit school at 15 to work as a cowboy.

He spent the next few years working on various ranches along the Texas Gulf Coast. In 1876, he began working on cattle drives, leading thousands of heads of cattle up to the railroad junctions in Kansas, where cattle sold for eight to ten times higher than in Texas. He soon met famed lawmen Wyatt Earp and Bat Masterson, striking up long-term friendships with them. Siringo soon afterward began working on ranches in the Panhandle when he first encountered Billy the Kid. As Billy the Kid’s notorious reputation grew in the neighboring New Mexico Territory, Siringo led a number of posses in pursuit of him, to no avail. He later wrote a biography of Billy the Kid, relying heavily on stories he picked up from Sheriff Pat Garrett, whom he met in his pursuits of Billy the Kid.

Siringo married in 1884 and returned to Kansas to settle down into a life as a businessman. Armed with a gift for storytelling and memories of his many adventures, he wrote an autobiography in 1885, A Texas Cowboy. But many more adventures await. He was in Chicago in 1886 when he saw the chaos of the Haymarket Riots and was determined to enter law enforcement. He soon picked up a job with the Pinkerton Detective Agency, with a recommendation from Garrett.

He was sent to some of the most remote reaches of the Rocky Mountains in his years with Pinkerton. Several of his early cases involved him tracking down wanted men. He devised numerous ways to track and capture criminals, including new ways of winning their confidence to get confessions or witness their activities first-hand. He increasingly worked undercover and refined his techniques, netting many arrests.

Only part of the Pinkerton Agency’s work involved pursuit of suspects or investigations. With thousands of employees, Pinkerton was effectively a private army, often hired by corporations in the 1880s and 1890s to break up strikes by force. In 1892, Siringo was assigned to infiltrate the Western Federation of Miners, who had been agitating for higher wages and shorter working hours for some time. The Couer d’Alene Strike, as it was called, grew increasingly violent. When a number of union leaders began plotting to attack mine owners, Siringo alerted authorities who had them arrested, ending the strike and temporarily ending the violence on both sides.

He was sent back to Idaho in 1905. Labor disputes had continued, resulting in one radical detonating a bomb, killing the state’s popular governor. Siringo was assigned to provide additional security for mine owners. In the emotional trial that followed, defense lawyer Clarence Darrow became the target of numerous death threats. At one point, a lynch mob gathered to attack Darrow. Siringo leaped forward to protect Darrow and pulled him away to safety, saving the attorney’s life.

Siringo continued to pursue outlaws across the West. One of his most interesting cases was the pursuit of Butch Cassidy and the Sundance Kid. Through Siringo’s clever infiltration of the Wild Bunch gang, he was able to disrupt the group, forcing the two leaders of the group to flee to South America.