Evelita Juanita Spinelli, known as "The Duchess," was born on October 17, 1889, in Kentucky, U.S. Details about her early life are scarce, but she eventually moved to San Francisco, California. Spinelli was reported to have been involved in various occupations, including working as a seamstress and allegedly participating in professional wrestling, though these claims remain unverified. She was also noted for her skills as a knife thrower. In San Francisco, Spinelli established herself as the leader of a criminal gang, taking in young, delinquent, homeless men, cooking and cleaning for them, and training them to be professional criminals. The men received a ten-dollar weekly allowance, with Spinelli receiving the majority of their ill-gotten gains. Her daughter Lorraine, known as "Gypsy," regularly used a honey trap to lure drunken men, who were consequently mugged.

In the late 1930s, Spinelli led a gang involved in various criminal activities, including robberies and burglaries in the San Francisco area. On April 8, 1940, two of Spinelli's protégés, Albert Ives and Robert Sherrod, killed Leland Cash during an armed robbery in San Francisco. Cash, who was hard of hearing, did not respond to their demands and was shot in the stomach. Fearing that Sherrod might confess to the police, Spinelli decided to eliminate him. She laced his whiskey with chloral hydrate, and after he passed out, he was beaten. The gang then dressed him in swimming trunks and threw him off the Clarksburg bridge into the Sacramento River to make his death appear accidental. However, the autopsy revealed no water in his lungs, indicating he was dead before entering the water.

Fearing for his own safety, Ives confessed to the police, leading to Spinelli's arrest. Ballistics matched the bullet that killed Cash to a gun owned by Spinelli. During the trial, her gang members testified against her, and on May 30, 1940, Spinelli, along with Mike Simeone and Gordon Hawkins, was found guilty of first-degree murder. She appealed the conviction in 1941, but the appeal was unsuccessful.

Spinelli's execution was initially delayed by Governor Culbert Olson, but after multiple reprieves, she was executed on November 21, 1941, at the age of 52, in the gas chamber at San Quentin State Prison. A week later, her common-law husband Mike Simeone and gang member Gordon Hawkins were also executed. Clinton Duffy, the warden at San Quentin, described Spinelli as "the coldest, hardest character, male or female, I have ever known."