Are you who you say you are?

That's the main question for Capture Technologies, a security and identity authentication company that's finding a steady increase in clients who need to know who they're dealing with.

In November, during the Cosco Busan oil spill, when 58,000 gallons of oil poured into the bay, Capture Technologies worked behind the scenes providing identity badges for clean-up crews. That allowed authorities to separate trained professionals from untrained if well-meaning members of the public who could have complicated clean-up efforts or even injured themselves.

Lawrence Livermore National Laboratory and San Francisco 911 already use Capture's services, and the company is embarking on its newest -- and perhaps most controversial -- project: San Francisco identity cards, which the city plans to issue to all residents.

The common ingredient: safety.

"You have a sense of mission that is unparalleled. You know what you're providing the marketplace is something that is going to protect people," said Lou Parrague, Capture's president.

If Capture now sees growth opportunities, it's hardly an overnight success. Established in 1948 under the name of US Audio, it specialized in audio recording for business and law meetings and stayed small for half a century.

Then came Sept. 11, 2001. After the fall of the Twin Towers , the United States demanded greater security meaures. The term "emergency-preparedness" was not a common word in the American lexicon before then, said Chanda Brewer, marketing director for Capture Technologies.

Nowadays municipal and corporate associations place high priority on security. Safety on campuses, in airports and on hospital grounds is a growing industry.

Capture Technologies thrust full force into this market. In April 2002, Parrague was recruited to be president. Under his leadership, the company took on a new name and new ambitions.

Parrague embraced the name because "we capture identity, we capture voice, we capture video."

The focus of the company broadened to corporate and city-wide security. Capture's products aimed to track people and enforce access controls. It also broadened beyond the Bay Area.

In the past four years, Capture Technologies has moved into Portland, Ore. , Los Angeles , and Phoenix . It acquired two competitors, Corporate Solutions and Business Equipment Corp. in 2006, and bulked up distribution deals with manufacturers. Clients have included American Express, Kaiser Permanente and the city of San Francisco .

The company now offers a range of digital technologies. It now boasts top-of-the-line voice, video, access controls and "embossing" -- creating a 3-D digital image of a person. Its digital recording and identity verification systems are its biggest sellers.

Tech support is a major draw for clients. Some clients even have specialized, 24-hour support agreements. "They're local and that's a plus," said Sharon Kennedy, RN, BSN and prehospital liaison at San Francisco General Hospital.

Kennedy needs immediate response for her work. Cross-country tech support isn't an option.

"If I have a problem, they actually show up in person -- not someone on the phone working me through the process." For the hospital environment, said Kennedy, this support makes all the difference.

Capture is working with the San Francisco Fire Department to equip firehouses with access control systems.

Revenue has grown steadily, but hasn't kept pace with the expansion in products and locations. But with a bigger profile in the industry, Parrague expects that to change. He has a five-year goal of hitting $20 million in annual revenue.

His employees, too, see big plans for the company. "I think the security director should be up there with the CEO and CFO," said Jeff Atkinson, Capture's account executive for San Francisco .

Such a move may not happen soon. But this industry expects a long life span.

Snapshot: Capture Technologies

What it does: Security systems for city, health-care and other industries.
HQ: Oakland .
President: Lou Parrague.
Founder: Bill Scott.
2007 revenue: $10.5 million.
2006 revenue: $10.3 million.
2005 revenue: $9.2 million.
Founded: 1948.
Web site: www.capturetechnologiesinc.com