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The boyfriend of Samantha Who? star Christina Applegate was found dead in his Hollywood apartment on Tuesday, celebrity website TMZ.com reported today.
Lee Grivas, a 26-year-old aspiring photographer, had been dating Applegate on and off for the last two years.
The actress told E! News in a statement she was "profoundly saddened" by Grivas' death.
"Lee was an incredible human being who was an extremely important and beautiful part of my life," she said.
"He is missed beyond words. He touched so many and I feel much sadness for his mother, brother and all of his family and friends."
It has not yet been confirmed what caused Grivas' death, but People.com quoted Lieutenant Fred Corral of the Los Angeles Department of Coroner as saying: "Grivas did have a history of drug abuse, and our investigator found a syringe at the scene."
However Lt Corral said no preliminary conclusions about the death would be made until a toxicology report was concluded.
Applegate reportedly began seeing Grivas in January 2006 after her then-husband Jonathan Schaech filed for divorce.
E! Online said reports indicated the couple split later that year but had been seeing one another again more recently.