Dillinger was sent to the Indiana State Reformatory in Pendleton, where he played on the prison baseball team and worked in the shirt factory as a seamster. Dillinger’s remarkable manual dexterity came into play just as it had during his time at the machine shop. He frequently completed twice his quota in the prison factory, and would secretly help fill other men’s quotas. As a result, he made many friends within the prison population. It was at the state reformatory that Dillinger met Harry Pierpont and Homer Van Meter, two men who would someday join Dillinger in his life of crime.
As his prison years went on, Dillinger’s wife and family visited him frequently. He often wrote letters to Beryl full of affection, “Dearest, we will be so happy when I can come home to you and chase your sorrows away…For sweetheart, I love you so all I want is to just be with you and make you happy…Write soon and come sooner.” But Beryl was not doing well with the separation. She obtained a divorce on June 20, 1929, two days before his birthday. He was devastated and later admitted the event had broken his heart.
Dillinger was dealt a second blow when he was denied parole. He had not been an exemplary prisoner, after having tried to escape a few times. But not seeing he was much responsible for his circumstances, he felt bitter and angry about the denial for parole. In a letter he wrote to his father in October 1933, he confided, “I know I have been a big disappointment to you but I guess I did too much time, for where I went in a carefree boy, I came out bitter toward everything in general… if I had gotten off more leniently when I made my first mistake this would never have happened.” He quit the baseball team, one of his few passions, and asked to be sent to Indiana State Prison in Michigan City, Indiana. Dillinger told prison officials it had a better baseball team, but the truth was he wanted to join friends Pierpont and Van Meter who had been transferred there earlier.
Dillinger found prison life much harsher and disciplined. He was surprised to see so many men his father’s age spending the rest of their lives in prison. He became depressed and withdrawn. He didn’t join the baseball team, but instead buried himself in his work in the prison shirt factory, producing double his quote to help other inmates.
It was during this time that Dillinger learned the ropes of crime from seasoned bank robbers. In addition to reconnecting with Pierpont and Van Meter, he became friends with Walter Dietrich who had worked with the notorious Herman Lamm. A former German army officer, Lamm had emigrated to the United States in the late 1800s. He was famous for planning his bank robberies with the precision of a military tactician. Dietrich had studied the man’s method well and was a good teacher, instructing his students in how to investigate the layout of a bank, the entries and exits, windows, and the location of the nearest police station.
Pierpont and Van Meter had longer sentences than John Dillinger but they weren’t planning on serving out their full terms. They had already begun planning bank heists for when they were out. Upon leaving prison, they would bribe a few key guards, get a few guns, and grab a place to lay low for awhile. But they would need money to finance their jail break. Knowing that Dillinger would be freed sooner than they, Pierpont and is colleagues brought him in on their scheme and gave Dillinger a crash course in the art of robbery. They gave him a list of stores and banks to hold up and contact information of the most reliable accomplices. They also provided him with guidance on where to fence stolen goods and money.
In May of 1933, the plan got an unexpected boost. Dillinger had been in the state pen for almost four years. He was notified by his family that his stepmother was near death. He was granted parole, but arrived home after she had died. Seizing on the moment, he joined up with a few of Pierpont’s men and began a string of robberies that netted nearly $50,000. With the aid of two female accomplices, Pearl Elliott and Mary Kinder, Dillinger put the escape plan in motion. He arranged for several guns to be packed in a box of thread, and smuggled into the shirt factory. The prison break was set for September 27, 1933.Having some time on his hands, Dillinger decided to visit lady friend Mary Longnaker in Dayton, Ohio, whom he had met earlier that year. Unfortunately, the police had been stalking him through much of this time as he gathered the funds for the prison break. After receiving a tip from his landlady, they stormed into Mary’s room and arrested Dillinger. He was on his way back to prison. In the meantime, Pierpont and his men escaped from Indiana State Prison and made their way to the gang’s hideout in Hamilton, Ohio.
Dillinger was incarcerated at the Lima, Ohio, jail under the care of Sheriff Jess Sarber and his wife, who lived at the jail building. The jail was just a little over 100 miles away from Pierpont’s hideout. He realized that with some cash and a few guns he would be able to spring Dillinger. Pierpont and two other men knocked over a local bank that had been previously closed due to the “bank holiday” enacted by Treasury Department. Armed with pistols, the three men approached the jail house just as Sheriff Sarber and his wife were finishing dinner. Pierpont knocked on the door and announced they were officers from the state penitentiary and needed to see Dillinger. When Sarber asked for their credentials, they showed him their guns. Sarber reached for a gun and Pierpont panicked and shot him twice. Mrs. Sarber gave them the jail keys and they sprang Dillinger. Sarber died a few hours later. This made all members of the gang accessories to murder.
Once Dillinger was free, the gang headed to Chicago to put together one of the most organized and deadly bank robbing gangs in the country. To pull many of the big jobs they had planned, Pierpont and Dillinger knew they needed heavy fire power, ammunition, and bullet-proof vests. To get the equipment, they headed to the police arsenal in Peru, Indiana. After casing the joint, Pierpont and Dillinger entered the arsenal, overpowered the three guards, and stole machine guns, sawed-off shotguns and ammunition.