Now, as he nears the end of his law enforcement career with the Fremont Police Department, Nelson again is stepping in front of the camera. Only this time he's going to be on the big screen.
Nelson, a police captain, has a speaking role in the upcoming film "Milk" about former San Francisco Supervisor Harvey Milk, the first openly gay elected official in the United States. Milk, who is portrayed in the film by Sean Penn, was assassinated 30 years ago by fellow Supervisor Dan White, played by Josh Brolin, who played Llewyln Moss in "No Country for Old Men."
Nelson plays a police officer, a role he lives every day. But the views expressed and the attitude exuded by his character are far from his real-life views, he said.
The role is a small one. Nelson speaks only four lines and his character's name is credited simply as "police officer." But the scene speaks volumes of the pressures gays in San Francisco felt in the 1970s.
In some cases the officers removed the badges from their uniforms so that they could not be easily identified, he said.
The role was intriguing, but a little disturbing to play because he is a real police officer, Nelson said.
"It was a little uncomfortable for me, but it was exciting to play a role in a major film," he said. "It was a two-edged sword."
The role fell into Nelson's lap earlier this year after a team-building exercise for the police department. A guest speaker stopped Nelson after the event, asked him if he was into modeling or acting, and then introduced Nelson to his agent.
Soon thereafter, Nelson signed on, took promotional pictures and auditioned for the "Milk" film. He tried out for three police officer roles and ultimately was cast as a villain cop.
"They treated me like I was somebody," he said. "It was just like you see on TV. I had my own trailer with my name on it."
But being in the film, which is not scheduled to open until November, was not the first time he appeared before a camera.
While attending California State University, Hayward (now East Bay), in the late 1970s and early 1980s, he did some modeling. After graduating with a degree in sociology, he moved to Los Angeles to pursue his modeling career.
After moving back to the Bay Area, he married, started a family and turned to law enforcement. Now in the twilight of his police career he intends to hang up the uniform within the next year Nelson thinks he'll pursue acting.
"I've got a few auditions lined up," he said.
Staff writer Ben Aguirre Jr. covers police and the courts for The Argus. He can be reached at 510-353-7011 or firstname.lastname@example.org.