Tyler Lambert, who had a history of substance abuse and depression, died last Friday (07May10) after embarking on a drugs binge before putting a shotgun in his mouth and pulling the trigger.
He had spiralled into a bout of depression as the anniversary of his mum's death loomed on the same weekend as Americans prepared to celebrate Mother's Day on Sunday (09May10), and detailed his heartache in a suicide note.
Lambert lost his actress mum to a drug overdose almost 11 years to the day, on 8 May, 1999.
Officials at the medical examiner's office in his hometown of Tulsa, Oklahoma confirmed his death was a "Suicide by a gunshot to the head", reports the National Enquirer.
His grandmother Joni Richardson tells the publication, "Tyler wanted to be with his mother. His father Lanny (Lambert, Plato's ex-husband) is devastated."
Plato starred as Kimberly Drummond in the hit 1980s TV sitcom, which catapulted her co-star Gary Coleman to fame.