Shemar Moore Remembers 'Young and the Restless' Star Kristoff St. John

S.W.A.T. star Shemar Moore shared a heartbreaking tribute to his former The Young and the Restless [...]

S.W.A.T. star Shemar Moore shared a heartbreaking tribute to his former The Young and the Restless co-star Kristoff St. John, who died Sunday at age 52.

"I lost my brother yesterday," Moore said. "I've never had a brother, but you were my brother. You showed me the way. You were my mentor, my inspiration. You showed me what true talent was. You showed me what humility was. I love you. I hate this. I love you, but I'm going to celebrate all your good."

Moore went on to convey how Young and The Restless fans should "celebrate this man" as an "iconic black man" in the daytime TV industry. To St. John's family, Moore wrote, "Cry your tears. I'm crying along with you."

"Mr KRISTOFF ST JOHN..... There is no ME without YOU!!!!! You are MY BROTHER!!! I LOVE YOU!!! Sleep my dude.... REST IN PEACE... I'll finish what YOU started!!! THANK YOU for YOUR HEART and TALENT," Moore wrote in the caption.

The former Criminal Minds actor also shared a few photos from his days on The Young and the Restless with St. John on Instagram.

"KRISTOFF ST JOHN.......... The most popular, Iconic, African American Soap Star EVER!!!!! ...... GIVE HIM THAT...... He EARNED IT!!!! ........ I LOVE YOU Stoff!!! There's NO me without YOU," Moore wrote in the caption to another photo.

Police told TMZ that paramedics rushed to St. John's Los Angeles home Sunday night, but was found dead at the scene.

The cause of death is still a mystery, as the autopsy obtained by E! News revealed little details. The outlet confirmed police were called to respond to a possible alcohol overdose, but the Los Angeles County Coroner listed the cause of death as pending until an "additional investigation" is finished.

At the time of his death, St. John was engaged to Kseniya Mikhaleva, who shared a message on Instagram expressing her shock.

"How did it happen ??? How ??? Why did you leave so early ???? and left me alone ..... I can't believe," she wrote Monday. "You were everything to me .... you were a loving father, a loving man, love??we should doing a lot of things in future......"

St. John is survived by Mikhaleva, ex-wife Mia St. John and his two daughters, Paris and Lola. He faced struggles with mental health after the apparent suicide of his son, Julian in 2014. In 2017, St. John was hospitalized for a mental health evaluation.

St. John was best known for playing Neil Winters for almost 30 years on The Young and The Restless. The series earned him Daytime Emmy Awards in 1992 and 2008. Moore played Malcolm Winters, Neil's half-brother, from 1994 to 2005 and in 2014.

Photo credit: CBS