The Jarvis estate was the home of a wealthy millionaire and the resting place of the valuable Neptune Cup. The Thinker once used his Thinking Cap to mentally force Jarvis' butler into giving him the Cup. Jay Garrick arrived to stop the Thinker, but the criminal was able to inacapacitate him with a wall of sheer mental energy. 
The Thinker once used his Thinking Cap to hypnotize the staff at the Keystone City Bank, enabling him to rob the bank teller's drawers. The staff believed that they saw dollar bills leaping from out of the till and float away. 
The Fiddler, the Shade and the Thinker once used their powers to force Jay Garrick and Barry Allen into robbing the Keystone City Museum. The Flashes were able to resist the power of the Fiddler's violin however by stuffing small gemstone into their ears. 
In the 1940s, Jay Garrick made frequent stops at the KCPD to drop off various criminals. In later years, Wally West did likewise during the time that he spent operating in Keystone as the third Flash.