Prosecutor Maurice M. Milligan had a burning hatred of Pendergast because the boss had supported Truman rather than Milligan�s brother Tuck in the 1934 Senate race. The prosecutor led the attack on the Pendergast machine by conducting a two-year election-fraud investigation. When completed, 259 of 278 defendants were convicted.
Despite the continuing investigations and trials, Pendergast�s slate of candidates again won election in 1938. Gov. Stark was urged to cleanse Kansas City of its wide open gambling and as he began to campaign for the U. S. Senate he found this to be the opportune time to strike at Pendergast. Stark felt he could gain support by his attacks on the Pendergast stronghold � the Kansas City Police Department. His boldest move was to put through legislation to return the department to state control. Stark believed that the prostitution, gambling, and illegal liquor activity in the city were protected by the Pendergast-controlled police department. After the Missouri General Assembly approved Stark�s legislation in July 1939, the newspapers began to fill with tales of corruption in the police department. While many officers refused to deny that corruption was taking place, they justified their participation because it granted them continued employment. In the aftermath of the departmental changeover, 50 percent of the police force was dismissed.
In Stark�s pursuit of Pendergast, he and Milligan traveled to Washington D.C. to confer with Elmer L. Irey, the chief of the intelligence unit of the U.S. Treasury Department. The Treasury man soon began an investigation into the O�Malley insurance compromise. Truman, at Pendergast�s urging, tried to replace Milligan when he came up for reappointment. The FDR administration frowned on this move and sensing a change in Missouri politics began to throw its support behind Stark and his anti-Pendergast campaign. By early 1939, five federal agencies were involved in the investigation of Pendergast.
The investigators confirmed the $750,000 payoff scam Pendergast had been paid by the insurance interests. The once unassailable Pendergast, the most powerful man in the history of Missouri politics, was indicted. Agents of the Internal Revenue Service also discovered that Pendergast had failed to pay income taxes from 1927 to 1937, and had doctored the books at eight companies where he held a major interest. A second indictment followed. Placed under such intense scrutiny, Pendergast�s health began to fail. He suffered a heart attack and over the next several years had surgery three times for abdominal problems.
In May 1939, Milligan presented his case against Pendergast in court. Due to the overwhelming evidence against him, Pendergast pleaded guilty to two charges of income tax evasion. He was fined $10,000 and sentenced to 15 months in federal prison on the first charge. On the second charge, he received three years, but was let off with five years probation. He was released from prison in 1940, but his career was over.
In addition to Pendergast, the others sent to prison as a result of Milligan�s investigations were Emmett O�Malley, Matthew Murray, Otto Higgins, the director of the police department, and Charles Carollo who oversaw the gambling interests in Kansas City.
Pendergast�s demise also signaled the end of the machine. Even Gov. Stark suffered as few voters respected him for betraying the man who had put him in office. Harry Truman, by stint of his own personal integrity, survived although his association with Pendergast would come under numerous attacks from his political foes. As Vice President Truman, he would cause a national uproar by attending Pendergast�s funeral in Kansas City in January 1945. Three years later, in one of the great political ironies of all time, Truman, the prot�g� of one of the most corrupt public figures in U.S. history, narrowly defeated crime fighter Thomas E. Dewey for President in 1948.