According to law enforcement experts, Matthew is the prototypical steroid user — in his 30s, white and worried about competing. In Matthew's case, he was trying to stay on top of a job that constantly forced him to face younger and stronger criminals.

"I look back on that and other scuffles, and I was not nearly as tough and strong as I once was," said Matthew, now a 33-year-old single father.

"It scared me to think how easily things could go wrong," said Matthew. "I kept thinking I am only getting older, and the criminals will always be young. I was looking for an edge."

'Juicing' Across the Country
From Boston to Arizona, police departments are investigating a growing number of incidents involving uniformed police officers using steroids. So-called "juicing" has been anecdotally associated with several brutality cases, including the 1997 sodomizing of Haitian immigrant Abner Louima in New York City.

Anabolic steroids are synthesized male sex hormones that promote muscle mass. When prescribed legally, medical steroids are used to treat growth problems in children, anemia and chronic infections like HIV.

Without a prescription, the use of anabolic steroids is illegal. Listed as a Schedule III substance along with morphine, opium and barbiturates, they can be just as psychologically addictive and dangerous.

Very little data are available on the number of adults who illegally use steroids, according to the federal Drug Enforcement Agency, because most abusers end up in private doctors' offices for depression or suicidal tendencies.

A common side effect of steroid use is violent, aggressive behavior that can contribute to poor judgment and even police brutality, according to medical experts.

Gene Sanders, a Spokane, Wash., police psychologist, estimates that up to 25 percent of all police officers in urban settings with gangs and high crime use steroids — many of them defensively.

"How do I deal with people who are in better shape than me and want to kill me?" said Sanders, who worked as a street cop in Los Angeles in the 1970s and saw steroid use soar in the 1990s.

Steroid use is on the rise, and not just among weight lifters and other athletes. An estimated 2.7 percent of all high school seniors have used steroids at least once, according to the National Institute on Drug Abuse, many of them women.

In the police community, cultural acceptance of bodybuilding and access to online suppliers make it easier for officers to obtain steroids.

Officers Propelled by Fear "Some of it is real and some of it is imagined on the part of the officers involved: fear, anxiety, wanting to do a better job," said Sanders, who consults with physicians across the country as director of the Police Stress Institute.

The temptation to find a "quick fix" is always present, said Sanders. Several older studies have placed police officers at the "bottom of the fitness scale," below firefighters and outranked by inmates, he said.

Typically, departments "turn a blind eye," to steroid use, according to Sanders.

The International Association of Police Chiefs Association did not return calls for comment, but at least one of those being investigated in the New York City probe is a high-ranking officer, according to local news reports.

"The body feels really comfortable and likes [the hormones]," said Sanders. "You feel better, feel more buff and feel more able to take on the bad people."

Indeed, Matthew felt the positive effects of steroids after only three months' use. His weight jumped from 170 pounds to 192 pounds, and he was able to bench-press 300 pounds from 225 pounds.

His habit — 500-700 milliliters a week injected into his deltoids, thighs or buttocks — cost about $500 a month.

"I was incredibly stronger," he said. "I never felt healthier in my life and woke up full of energy and felt it throughout the day. Never once did I feel out of control."

"Maybe I was a little edgier," he added. "The kids got me upset a little more and I was less tolerant, but never to the point where I would physically do anyone harm."

Still, said Sanders, steroid users tend to think "more is better" and don't know where to draw the line as they build bulk. Users typically combine steroids with a combination of drugs in a phenomenon known as "stacking," and "cycle" on and off the drugs to avoid building a tolerance.

"They can go from being calm and collected to raging bulls," said Sanders. "There is also a subcategory of these folks like the crazy Vietnam veteran. They think that if they appear crazy, people will back off."

But even short-term use of steroids can cause damage to brain tissue, which never grows back. And according to the National Institute of Drug Abuse, steroid abuse can cause internal organ damage, jaundice and high blood pressure.

Men can also experience testicle shrinkage and breast development. Women can see side effects of facial hair growth, menstrual changes and a deepened voice. Teenagers may stop growing.

Research shows extreme mood swings can occur as a result of taking steroids, leading to violence. Users may suffer irritability, delusions and impaired judgment.

"When they are used in excess, the individual crosses the line from adding muscle mass to rage or aggression or suicide," said Dr. Robert S. Gotlin, director of orthopaedic and sports rehabilitation at Beth Israel Medical Center in New York City. "Suppose that person is carrying a gun."

"The results are so profound, and it's so accessible," he said.

In Matthew's case, he obtained steroids from a friend. At least 10 other officers in his 75-member department were users when he started taking them. Steroids are readily accessible at gyms — "if you know the right people" and online, he said.

"When I first became a police officer, I worked out," said Matthew. "As I got older, I ran into bigger kids on the street who were into all kinds of drugs. They don't feel the pain. I thought if I could, I could have something to make me feel better about myself, I could handle it."

 Because of his felony conviction, Matthew, who had no previous criminal record before his arrest, will never be able to work in law enforcement again. But he hasn't touched steroids since, primarily because he wants to be a role model to his children, who are 4 and 7.

Though he is proud of his 10 years of police work, Matthew now understands how steroids can create monsters out of police officers who are not responsible.

"There are rage issues," he said. "And there's the mental part of it that makes you think you are invincible."