The last unused bankheist mythology, George Leonidas Leslie's wiki writes its own screenplay
Above image from article Why Thieves are Photographed in the book Professional Criminals of America 1886
George Leonidas Leslie was an architect turned robber who was known to law enforcement and the underworld as a criminal genius.
As a young man Leslie studied architecture at the University of Cincinnati. He graduated with high honors. After graduation and the deaths of both his parents in 1867, George gave up his architecture business, closed the family brewery, and moved to New York. Searching for something more exciting and challenging, he joined the criminal underground. For 10 years he was the most successful bank robber in New York state and was perhaps one of the most notorious in U.S. history. By 1874 he was at the head of the most successful gang of bankrobbers known. However, his involvement in these robberies was not known until after his death in 1878. As members of his gang were caught, they told police who had masterminded the robberies. Until then, George Leonidas Leslie lived a life among the rich and famous of his day.
In 1872, Leslie came to Philadelphia, and, masquerading as an IRS agent by the name of George L. Howard, stayed at the boarding house of Mary Coath while planning the heist of the South Kensington National Bank. It was there he met her 15 year-old daughter, Mary Henrietta Coath. Young Mary was a dark haired beauty, well brought up and well educated, but she fell for Leslie, and they were married after a short courtship. George and Mary moved to New York, where they lived the life of a society couple, with no hint of George's true occupation. There is debate whether Mary was fully aware of criminal activities, or if she was blissfully ignorant. One source said she became aware of his true criminal occupation around 1874, and was only too happy to share in his fortunes. Another source says she was unaware of his activities until after he died. Mary returned to Philadelphia after Leslie's death, and died in her mother's boarding house in 1890, at the age of 35.
Leslie would spend up to three years planning a robbery. After selecting his target (usually a bank), he would obtain, if possible, the building's blueprints. His architectural background allowed him to build scale models of his intended targets. He would sometimes rent a safe-deposit box, or open accounts with a particular bank, which gave him an excuse to spend time in the building and observe its layout and operation. Othertimes he would get one of his men hired as a watchman or porter, and this spy would gain the information for him.
Leslie had a model of almost every make and model of vault and safe used in the United States. Before a robbery would be committed, Leslie would find out what type of vault or safe his target used, and then spent months figuring out how to open it without the combination. (Gangs of New York, 188) He used a device that he called the "little joker" that, when placed inside a bank safe's lock, could record the numbers that made up the lock's combination. This required George to enter the bank at least twice prior to executing a robbery, once to place the 'joker," and a second time, to retrieve it.
When he was certain that the robbery could be committed without being caught, Leslie would select his accomplices and explain to them how to execute the robbery. Sometimes he would set up a room to resemble the inside of the target so that his men could practice the robbery while Leslie watched.
From 1874-1884 it is estimated that Leslie's gang was responsible for 80% of America's bank robberies. (Gangs of New York, 186) During this time he planned and executed over a hundred robberies and stole between seven and twelve million dollars.
In his later years he became a consultant for other robbers. For a price he would travel to wherever the robbery was to take place and plan how the operation should go. This part of his life did not last very long. He had fallen for a couple of women, and by 1878 was spending more time with them than he was on his work. His gang lost faith in his abilities, and on June 4, 1878, his partially decomposed body was found at Tramp Rock, Yonkers NY. His murder was never solved, although there is speculation it was related to Leslie's involvement with the sister of one of his associates.