Nearly all Fairfax County police officers who spend time on the street can recall plenty of moments -- dealing with a terrified crime victim, a frenzied witness, a lost child -- when they thought, "Man, I wish I spoke Spanish."

Officer John Keating, who patrols in the McLean district, remembered being the first officer to reach a woman who had been sexually assaulted. "She was screaming," Keating said, but as he tried to calm her, he was unable to quickly get a description of her attacker because she spoke only Spanish. Police cars zoomed in and a police helicopter circled overhead, but by the time Keating was able to get a description, the suspect was gone.

"He could've walked right by us," Keating said, "and no one knew."

Keating was one of 10 officers selected by commanders for a pilot program at the Diplomatic Language Services school in Arlington. The officers left the streets from January to June for 22 weeks of full-time immersion in Spanish: six hours of class and two hours of homework a day, five days a week.

A graduation ceremony was held Friday at police headquarters. Police brass congratulated the students and expressed hope that the language immersion will help the police communicate with the county's rapidly growing Latino community.

County statistics show that about 30 percent of Fairfax residents are foreign-born or children of recent immigrants, and 25 percent of those have limited proficiency in English. About 12 percent of county residents are Hispanic, according to estimates.

Less than 4 percent of the 1,332-member Fairfax police force is Hispanic.

"I would love to find ways to recruit people with the native language skills," said Chief David M. Rohrer, who has regularly cited adding Hispanic officers as one of the goals of his now year-long tenure. "But absent that, doing nothing was not a very good option. So we felt the best option was to build the base of officers who speak the language proficiently."

The need to speak Spanish is not limited to responding to crime scenes. "We wanted to talk with people as people," said Maj. Thomas Ryan, who helped organize the first Spanish classes, "to talk about community issues with people. It all comes down to trust. Sometimes we don't have a relationship with people, not because they don't like us, but because they don't know us."

Rohrer said he suspected that crime in non-English-speaking neighborhoods is underreported, due either to mistrust or misunderstanding caused by the language barrier. He said robberies or fraud against day laborers and domestic violence may not be reported regularly.

"We hope we learn more about what happens in neighborhoods" by putting more Spanish-speaking officers in them, Rohrer said.

In addition to instruction, reading and tests, the officers went to Spanish-speaking neighborhoods for chats with residents. The officers would sit, in plain clothes, with parents at an elementary school and listen to them talk about anything, not just crime or police issues.

When the 10 officers, chosen from a group of 90 applicants, returned to the street last month, they immediately put their skills to work. Officer Rebecca Gray, assigned to the Mason District, said she encountered a man on her first day whose car had been stolen. He spoke no English.

In the past, Gray would have had to find a phone or use her personal cell phone to call an interpreter and conduct a lengthy interview, involving repeatedly handing the phone over, and then over to the car's owner.

"I think it's a huge thing for the community to see us making the effort to speak Spanish," Gray said.

Officer Gary Beaver, assigned to the Fair Oaks District, said being able to converse directly with someone allows an officer to make important observations. "The body language, the head nods, the breathing," Beaver said. "You can't get that on the phone."

The officers are intent on using their new skills so they don't fade. Officer John Debonia said he uses Spanish every day on his beat in Reston. If he doesn't use it on a call, "I'll find someplace in Reston, just stop at a soccer field and ask somebody to help me practice," Debonia said.

Ryan and Rohrer said other area departments are watching Fairfax's experiment to see whether it would benefit their officers. "This was a good pilot," Ryan said. "If I can get good feedback six months from now, I'm absolutely going to be excited to try it again."