Dr. Glennon Engleman was a St. Louis dentist who killed 7 people for their life insurance and unpaid dentist bills. He used a variety of means including car bombs and shooting. He collected the insurance by killing his former male patients, and then wooing their widowed wives to give him money to invest for business purposes. Former female patients who didn't pay their bills were just killed. He was eventually caught by a would-be female victim who wore an undercover microphone. He was sentenced to three life terms.