The brother of "Law and Order: SVU" actor Richard Belzer leapt to his death Wednesday from his Upper West Side building, a law enforcement official said.

Leonard Belzer, 73, jumped from the 16th floor of the West 94th Street apartment building at 6:45 a.m., the official said, adding he left a note.

The contents of the note were unclear.

Belzer's death was confirmed by Richard Belzer's rep, who said the actor was in seclusion at his home in France and could not be reached for comment.

Leonard Belzer had been married to Emily Squires, a director and producer of "Sesame Street, " who died in 2012 at the age of 71.

Alex Pagano, 42, worked with Leonard Belzer several years ago at MJI Broadcasting in midtown. He called the news of his death "shocking and sad."

"He always seemed like a jovial guy," Pagano said. "He was one of the good people to work with. He was very approachable."

Belzer, like his famous brother, was into conspiracy theories, Pagano said, adding that he would regularly talk about health and wellness, too.