The "Diary of a Mad Black Woman" star landed his big break on the drama and publicly thanked St. John for showing him the ropes after his pal's death last month (February 2019).
The two stars played siblings on "The Young and the Restless", and Shemar insisted Kristoff, who played Neil Winters from 1991, was the closest thing he had to a real-life brother.
"I'm raised an only child, but Kristoff is truly the closest thing to a brother and a brother's love and a brother's mentorship that I've ever known," he wrote in a statement. "He didn't have to embrace me the way he did... If he hadn't embraced me, I would have never got my sure footing in the beginning days..."
"I will always give Kristoff that credit... Kristoff, day to day to day, he rooted for me. He didn't have to.... but he rooted for me; he helped me; he held my hand; he said, 'Stick with me, bruh, I'm going to show you the way and then you do what you're doing (sic)'."
Moore, who made his last appearance on the drama as Neil's brother in September, 2014, will reprise his role as Malcom Winters on the show for two episodes airing next month (April 2019), while former "The Young and the Restless" stars Victoria Rowell and Mishael Morgan will also be coming back for a special tribute episode on 29 April.
The news emerged at the same time as the Los Angeles coroner's report regarding St. John's cause of death was released, revealing he died from heart disease and an accidental alcohol overdose, according to TMZ.