Baltimore police Sgt. Mike Dunn was among the first believers.
On a dreary April evening 21 years ago, Dunn pulled over a van for what he thought was a routine traffic stop on South Hanover Street. What he found was a driver pointing a revolver directly at him.
Boom. Boom. Boom.
One bullet hit him in the left arm, another lodged in his leg. A third slammed into his chest.
Dunn fell to the ground, wounded but alive - thanks to the synthetic body armor the department had issued him.
"They told me ... if it was not for the vest, I would have definitely been killed," said Dunn, 45, a fifth-generation city police officer.
He found out later that the gunman had kidnapped, raped and robbed two women who were in the back of the van.
Dunn is believed to be the first city officer saved by the protective vest, an inch-thick piece of synthetic material worn under a shirt. He is a member of a select group of survivors that, as of Monday afternoon, now includes Detective David F. Azur.
Azur, a 7 1/2 - year veteran and member of the Regional Auto Theft Task Force, was wearing body armor when he was shot in the chest at point-blank range Monday while trying to arrest a car-theft suspect in the 1200 block of W. North Ave. He was treated at a hospital for a bruised chest and released two hours later.
After shooting Azur, the suspect - identified yesterday as Vernon Tyrone Horton, 38, of the 800 block of Bethune Road in Cherry Hill - shot and killed himself. Horton, who had a lengthy criminal record for violent crimes, was wanted for violating a home-detention sentence, police said.
"Boy, did that bring back memories," said Dunn, a 27-year veteran who is now assigned to the tactical division and in charge of the police honor guard. "First I said, 'God, not another funeral.' Then I heard he had his vest on."
Baltimore was the second city in the nation - after San Francisco - to issue body armor to all its officers in 1977.
Officials estimate that since the late 1970s more than a dozen officers have survived violent encounters because of body armor, which is as much a part of the uniform as the badge and holster.
Baltimore police have required officers to wear their vests since they were issued. But Dunn said that in the 1970s, before crack cocaine hit Baltimore, bringing with it an epidemic of violence, many officers ignored the order.
Today, police are taking the order seriously. Supervisors inspect officers at roll call, and those without vests face disciplinary action.
But most officers - even those who spend most of their time behind a desk - wear the vests, which weigh between 3 and 6 pounds.
"It does not matter, because if they go out to lunch you can always encounter a suspect with a gun who may want to do you bodily harm," said Sgt. Vincent Moore.
Moore, a 12-year veteran, was an undercover drug detective in August 1989 when he was ambushed in an alley between Greenmount Avenue and Proctor Street.
The gunman, armed with a .357-caliber handgun, shot Moore in the arm and chest.
Moore credits his survival to the body armor.
Besides the city Police Department, Maryland State Police and Anne Arundel County require officers to wear body armor while on duty.
Baltimore and Howard County police departments have no mandatory body-armor policy, but commanders "strongly recommend" its use.
After he was shot, Dunn encouraged other officers to wear the vests, which have not always been popular because they were bulky and poorly ventilated.
In 1981, he starred in a training film called "Protecting Society's Protectors" made for DuPont, the company that manufactures Kevlar, one of the first materials used in body armor.
While the video dealt primarily with body armor's ability to stop bullets, Dunn's younger brother, Paul Dunn, learned another use for the vests.
In May 1987, when he was a patrol officer in the Southeastern District, Paul Dunn stopped two men at Boston Street and South Lakewood Avenue. They grabbed his holster, and flipped him to the ground.
The men then took a hammer and began beating him in the chest and head.
"I remember trying to crawl inside that vest," Paul Dunn said. " I felt like a turtle trying to get in there to get away from the blows."
Paul Dunn, 43, who retired from the department in 1993, had to get 100 stitches in his head and undergo two surgeries. Doctors told Paul Dunn the blows would have killed him if he had not been wearing his body armor.
David Kotwick, a vice president of Second Chance, a company that manufactures body armor, including many of the vests that have been issued to city officers, said the equipment causes bullets to fracture and disperse on impact.
The material also distributes the force of any type of impact across the body armor, lowering the chance of serious injury or death from beatings.