How train robberies in the 19th century helped build up law enforcement agencies in the west

From a podcast I listened to in the car recently. Two gangs and one individual who robbed trains and stagecoaches in the west and were successful for a period of time because of the lack of law enforcement agencies - notable federal agencies. The only available force initially was the general population that would create vigilante forces to capture and punish these individuals. 

One of my themes in class is that governmental activity is often related to actual events. Here's anb example. 

- Wikipedia: Reno Gang. 

. . . a group of criminals that operated in the Midwestern United States during and just after the American Civil War. Though short-lived, the gang carried out the first three peacetime train robberies in U.S. history. Most of the stolen money was never recovered.

The gang was broken up by the lynchings of ten of its members by vigilante mobs in 1868. The murders created an international diplomatic incident with Canada and Great Britain, a general public uproar, and international newspaper coverage. No one was ever identified or prosecuted for the lynchings.

- Wikipedia: James–Younger Gang.

For nearly a decade following the Civil War, the James–Younger Gang was among the most feared, most publicized, and most wanted confederations of outlaws on the American frontier. Though their crimes were reckless and brutal, many members of the gang commanded a notoriety in the public eye that earned the gang significant popular support and sympathy. The gang's activities spanned much of the central part of the country; they are suspected of having robbed banks, trains, and stagecoaches in at least eleven states: Missouri, Kentucky, Tennessee, Iowa, Kansas, Minnesota, Texas, Arkansas, Louisiana, Alabama, and West Virginia.

- Wikipedia: Black Bart.

. . . an American outlaw noted for the poetic messages he left behind after two of his robberies. Often called Charley by his friends, he was also known as Charles (or C.E.) Bolton.[1] Considered a gentleman bandit with a reputation for style and sophistication,[1] he was one of the most notorious stagecoach robbers to operate in and around Northern California and southern Oregon during the 1870s and 1880s.

__________

- Frontier Justice.

- Extrajudicial Punishment. 

- Wikipedia: Train Robberies.

- Wikipedia: Vigilance Committees.

-  Extrajudicial Killings.

- Wikipedia: Pinkerton detective agency.

 Lynch law

vigilante Justice / vigilance committee 

Lynch mobs

Free blacks