Helen Morris List was 45 when she was killed at home in Westfield, New Jersey, on November 9, 1971. Her husband, John Emil List, is described as the perpetrator who then murdered his mother, Alma, 84, and the couple’s three children—Patricia, 16; John Jr., 15; and Frederick, 13—after they returned home one by one.

The bodies of Helen and the rest of the family were reportedly found on December 7, 1971, placed on sleeping bags in the mansion’s ballroom. Investigators say John List took steps to delay discovery, including stopping mail and newspaper deliveries, notifying schools that the family was away, and cutting his own image out of family photographs before disappearing. He later lived under the name Robert Clark in Colorado and remarried.

A 1989 broadcast led to a tip that resulted in John List’s arrest on June 1, 1989, in Richmond, Virginia. He was extradited, tried, and convicted of five counts of first-degree murder in 1990 and received five consecutive life terms; he died in prison in 2008.