Prisoners note a curious change in the fresh-faced, often idealistic guards who first come to work in penitentiaries. After a certain amount of time, the guards begin to resemble -- often deliberately -- the inmates. The idea that the criminal could subvert the man of law is inconceivable to the guard, let alone the cop. Yet the process is critical, argues PNS associate editor Joe Loya, to answering the question posed by New York Mayor Rudolph Giuliani as his city grapples with the torture of a detainee by police: how can cops behave criminally? Loya, a freelance writer in Los Angeles, is at work on a book about his experiences in prison.

LOS ANGELES -- I never thought Jimmy Smits looked like a NYPD cop. He's a pretty boy. But Hollywood rarely gets the law enforcement look right. New York police officers look more like those photos of Officer Justin Volpe and Office Charles Schwarz -- the men accused of shoving the wooden handle of a toilet plunger up Abner Louima's rectum while shouting "nigger!"

New York Mayor Rudolph Giuliani is searching for an explanation for how peace officers, sworn to protect and serve, sat around and did nothing while Mr. Louima screamed under torture. How, the Mayor wonders, could they behave criminally?

I have a clue, Mr. Mayor. It has something to do with the dead-eyed, steely-stare of those two cops in the photographs.

I used to sit in my prison cell and remark to friends that our jailers sure looked a lot like us. Which isn't really surprising. They spend a third of their lives in jail. They could honestly be accused of choosing to go to the slammer.

When I spent seven years in prison for bank robbery, I saw a lot of new correctional officers come into the prison, fresh-faced, young, eager and sometimes a bit idealistic. We inmates referred to these green guards as "fish." (That's also what we called first-time offenders who came to prison unaware of what awaited them.) "Fish" derives its meaning, I suppose, from the metaphor of small fish in predatory waters.

I think often of one "fish" -- a prison guard at a Federal Penitentiary in California. But he could have been any prison guard -- in Folsom, California, or in Lewisburg, Pennsylvania. He was a momma's boy when he first arrived at the penitentiary.

He took seriously his job as a guard. Medium build, he didn't seem to care much about his appearance. He showed up to work in half-pressed clothes. Wore his hair parted down the middle and long around the ears. Brought a sack lunch with an egg salad sandwich along with a tupperware bowl filled with a thick slice of momma's fresh baked apple pie.

At first he was uncomfortable with his power. Wouldn't yell loud at mail call. If an inmate talked nicely to him, he tended to cut the guy some slack on the premise that kindness deserves a just turn.

But the boy soon realized that he was living among hard-core men who considered him gullible and a sissy. He woke up in prison, like many men before him who transformed their lives. Except his change went the other way.

He began to wear sharply-creased clothes -- convict style. He cut his hair and began to comb it slicked back, again, convict style. He grew a thick "walrus-brush" moustache, convict style. And he became obsessed with muscle the same way a convict does.

He began to pepper his conversation with gutter-level profanity. He lifted weights after work and would compare his workout techniques with brawny inmates, referring to smaller bodies as less than manly. He behaved the way veteran convicts expect wanna-be-tough-guys to act -- big-eyed and obvious, watching how real mobsters behave, then mimicking their pose, swagger and speech habits.

It never worked the other way around. Inmates didn't begin to look like the fresh-faced boys who first came to law enforcement. The sons of good families were the ones who turned distrustful of everything. We were already suspicious.

So they began to resemble us in look. Ironically, they also adopted our contemptuous attitude toward the "good guys." Guards would use words like "rat" and "snitch" to describe those officers whose job it was to investigate rogue prison guards.

I hear a boyhood friend, an ex-LAPD officer, talk about Internal Affairs with venom, as if those police officers are subversive agents seeking to undermine, rather than uphold, the law. He doesn't know how much his insults sound like the ones criminals use for all LAPD.

Whenever I or one of my friends would come across some really sadistic guard, we'd gather together and console ourselves with the notion that he would succumb to the hazards of his job. We'd say, "Don't worry about him, he'll get his. He doesn't know it yet, but he will soon be a lonely and miserable f..k. Law enforcement guys have the highest rate of spousal abuse and divorce of any profession, not to mention suicide. And if they don't kill themselves, they become huge boozers. Oh yeah, these guys are real pieces of work. They will hate themselves, AND their wife and kids will hate them too."

They would begin to show our same signs of stress precisely because the idea of becoming like us was inconceivable to them.

It's a cliche to simply say that the law enforcement officers are just another gang. But becoming like the criminal is exactly what happened to the NYPD guys involved in torture.

If you still doubt it, take a closer look at that picture in the newspaper. It looks almost exactly like my mug shot.