It looks like four presidents were assasinated for trying to mess with the country's finances (source: www.uhoh.com):
1862 - Lincoln's Debt Free Greenbacks
1881 - President Garfield was assassinated shortly after declaring that whoever controls the supply of currency would control the business and activities of the people
1901 - Wiliam KcKinley, President, was assassinated. He had been recommending the gold standard.
1963 - Kennedy
1. Crossed the Fed and created debt free money.
2. The day after Kennedy's death, Johnson recalled and destroyed all of Kennedy's debt free money.