Pet cemetery owner Dorothy Lou Thompson was in a legal battle to reclaim her Louisiana land when she mysteriously vanished from her home in 1985. Less than a month later, her body was found in the Mississippi River.

Thompson’s murder remained unsolved for more than three decades until two unexpected witnesses came forward to help authorities crack the case. But there was a supernatural twist: Both of them claimed they were being haunted by Thompson’s ghost.

The new HBO docuseries The Pet Cemetery Murders: A Ghost Story revisits the shocking murder and lengthy investigation to catch Thompson’s killer. Here’s everything you should know about the former cold case.

Dorothy Lou Thompson was born on September 1, 1924, in Oklahoma City to Grace and Arthur Wynne. While Arthur was her biological father, she grew up calling her mother’s first husband, John Thompson, “Daddy Jack” and even took his surname, according to NOLA.com .…