Brenda Shouey told the San Francisco Chronicle the finger belonged to her son, who had the digit severed in a work-related accident in Las Vegas.
Shouey's son worked with James Plascencia, the husband of Anna Ayala, who authorities claim used the 1 1/2-inch-long body part in an effort to force Wendy's to pay a financial settlement. Ayala has been charged with attempted grand larceny.
Authorities determined the finger was from a co-worker of Plascencia, but didn't identify the man. The Chronicle said the man's mother confirmed his identity after receiving a call Monday night from her son.
She said her son didn't know of the plot against Wendy's but she told the Chronicle, "He had a money problem. He owed $50 to this character, James."
Ayala claimed she found the finger tip in chili she bought at a San Jose, Calif., Wendy's in March. The fast-food chain says the incident cost it about $2.5 million in sales.