SAN DIEGO (NEWS 8) - Search volunteers on Thursday went door-to-door in Scripps Ranch hoping to turn up any clues that may lead them to a man who went missing one week ago.

Taiheng Sun, 85, was last seen at his Scripps Ranch home last Thursday morning, but the effort to find him has not slowed down.

Searchers focused on a neighborhood where cameras captured a man who might be Sun being let of a car over the weekend.

About 120 Scripps Ranch Civic Association volunteers knocked on 450 doors looking for any trace or home surveillance video to corroborate Sun's sighting in the Legacy neighborhood.

Volunteer drone enthusiasts lent their services Wednesday to ongoing efforts to locate Sun. Operators of the camera-equipped flying machines were scanning open areas around his home.

A surveillance camera captured images of Sun walking to the east on Stonebridge Parkway about 8:30 the morning he went missing. He was clad in black pants, a blue long-sleeved shirt, white shoes and a blue baseball hat, and was carrying a white jacket.

Police also released video of a person, possibly Sun, being dropped off about 3 p.m. Saturday in the 11000 block of Legacy Canyon Place by someone driving a beige 2012-2013 Ford Taurus, according to San Diego police Lt. Mike Holden.

The person who gets dropped off lingers in the area for at least 30 minutes before the sun's reflection obscures the camera's view, Holden said.

Relatives of the Maple Grove Lane resident told authorities he had been depressed recently and had expressed suicidal thoughts. He does not drive or have access to other transportation, and knows no one in his neighborhood outside of his family, they said.

Sun is described as a 5-foot-6-inch, roughly 140-pound Asian with gray hair and brown eyes. He speaks very little English, according to San Diego police.

The Scripps Ranch Civic Association said they will debrief on Friday and follow up with police to decide where to search next.

Anyone with information on Sun's whereabouts was asked to call police at (619) 531-2000.