Karl Gustav Hultén was born in Sweden in 1922. Before enlisting in the U.S. Army following the attack on Pearl Harbor, he worked as a grocery clerk and mechanic. While stationed in England during World War II, Hultén deserted his unit and went AWOL. Assuming the alias "Ricky Allen," he portrayed himself as both an officer and a Chicago gangster, fabrications that he used to impress and manipulate those around him. ​

On 3 October 1944, Hultén met 18-year-old Elizabeth Marina Jones in a tea shop in London. Jones, who had run away from home at thirteen and had a history of being beyond parental control, was captivated by Hultén's fabricated tales of gangster life. The two quickly formed a partnership, engaging in a series of violent crimes over the next few days.​

Their crime spree began with the robbery of a nurse whom they knocked over while she was cycling along a country lane. They then picked up a hitchhiker, whom they assaulted, robbed, and threw into a river, though she survived. The culmination of their crimes occurred on 6 October 1944, when they hailed a taxi driven by George Edward Heath, a 34-year-old unlicensed cab driver with a distinctive cleft chin. After directing Heath to a secluded area near Staines in Middlesex, Hultén shot and killed him. They stole £8 from Heath, which they spent at a dog racing event the following day. ​

Hultén's reckless behavior continued as he attempted to procure a fur coat for Jones by attacking a woman in the street. This act drew the attention of the police, leading to his narrow escape in the stolen taxi. Eventually, authorities apprehended Hultén after discovering the stolen vehicle in his possession. Jones, overwhelmed by guilt, turned herself in to the police and confessed to their crimes. ​

Both were tried and found guilty of Heath's murder. Hultén was sentenced to death and executed by hanging at Pentonville Prison on 8 March 1945. Jones received a reprieve and was released from prison in May 1954.