Kergan was last seen leaving the Night Spot Lounge on Plank Road in Baton Rouge, Louisiana on November 28, 1984. He was accompanied by Leila "Erika" Mulla, a teenage exotic dancer, at the time. Kergan was carrying $2,000 in cash when he disappeared. He has never been heard from again. His late model pink Cadillac was later found abandoned in Metairie, Louisiana, with puddles of blood in the trunk.

Authorities believe Mulla and her boyfriend, Ronald Delton Dunnagan, murdered Kergan inside their apartment on Byron Street on the night of his disappearance. They fled the area for Las Vegas, Nevada after his disappearance. When authorities searched Mulla and Dunnagan's apartment, they found evidence of a violent struggle, including bloodstains. Entries in Mulla's diary indicated she was planning to murder Kergan.

Mulla and and Dunnagan were arrested and charged with his homicide. Authorities believe Kergan was murdered inside an apartment in the 2900 block of Byron Street, sometime after 2:00 a.m. on November 29. Blood and other indications of a violent struggle were found inside the apartment. When questioned by police after her arrest, Mulla implicated Dunnagan in Kergan's homicide. However, both defendants were released three months after their arrest and the charges were dropped. Mulla refused to testify against Dunnagan, and Kergan's body could not be found even after one of the most extensive searches in Baton Rouge history. Prosecutors did not believe they had enough evidence to convict Mulla and Dunnagan of murder.

Kergan and his brother co-owned a chain of Sonic drive-in restaurants in southern Louisiana in 1984. He was married in 1984 and has a son. Kergan was declared legally dead in 1986. He has never been located, but foul play is suspected in his case due to the circumstances involved.