His criminal career started at an early age. At age eight he was arrested for drunk and disorderly conduct. At age eleven, he was put into reform school for burglaries. Carl didn't like this, and proceeded to burn down the reform school, causing over $100,000 worth of damage. According to Carl, he learned all of his criminal attributes in reform schools and prisons, and proceeded to use this knowledge on anyone and everyone who crossed his path.

After serving a three year sentence at Leavenworth Prison, he went on a killing spree which spanned two continents. On one occasion he hired eight black workers to help him hunt crocodiles in Africa. Instead, he killed the men, sodomized their dead bodies, and fed them to the crocodiles. On another occasion he rented a yacht and invited sailors aboard, promising them free liquor. Carl drugged, raped, and slit the throats off all the sailors, then threw their bodies overboard.

On June 16, 1928, he strangled a New York woman for fun. Then on August 16, 1928 he was arrested for a string of burglaries and sent back to Leavenworth Prison. He said once in prison, he would kill the first person who crossed him. His unsuspecting victim was Robert Warnke, a laundry foreman in the prison. He crushed his skull on June 20, 1929, and was sentenced to hang for this crime.

While awaiting his sentence during the last part of 1929, Carl confessed to 21 murders, countless felonies, and more than one thousand acts of sodomy. No one was aware of these crimes until he confessed to them. He said "for all these things, I am not the least bit sorry."