Cummings was convicted on 13 May 1998 of voluntary manslaughter in the death of her boyfriend, Argentine polo player Roberto Villegas, and was sentenced to 60 days in jail and ordered to pay $2,500; she was released after serving 57 days.
Cummings and her fraternal twin sister, Diana, are the only children of billionaire arms dealer Samuel Cummings (1927-1998). After the family moved to the United States, Samuel Cummings bought his daughters a lavish estate in Warrenton, Virginia he named Ashland Farms. It was here that Cummings shot Villegas on 7 September 1997. She told the 911 dispatcher and police that he had turned abusive towards her, threatening her with a knife. Villegas was found with a knife crossing his arm. Cummings had cuts on her arm, which police suspected were self-inflicted. She was arrested on charges of homicide.
Ms. Cummings sold the 340 acre Ashland Farm estate on the edge of Warrenton Fauquier County, Virginia for $4.9 million in 2004. She and her twin sister Diana moved to the 450 acre LeBaron Farm in Culpeper County, Virginia. Their manor house, designed by the firm of Versaci Neumann Partners, won recognition in the 2006 Washingtonian Residential Design awards.
In 2004, Lisa Pulitzer wrote a book on the case called A Woman Scorned.