I guess Criminologists collect crimes, just like physical anthropologists collect bones. I love hearing about a new way to commit credit card fraud, or an ingenious money laundering scheme, or a computer crime so complex it has to be charted out on a piece of paper.

So, it's not surprising that lying flat on my back on a chrome table, I looked up at the man doing an x-ray of my neck, and asked: "What kinds of crimes do x-ray technicians get up to anyway?"

"Not a lot," he answered. "There's so much monitoring of what we do, it's not really possible to commit a crime."

Now, after spending most of my adult life around crime, criminals and criminologists, I knew that anybody in any profession who wanted to commit an occupation-related crime could figure out a way to so. X-ray technicians were no different from anybody else.

"Come on." I persisted. "There must be something."

He thought a moment, while he positioned the enormous machine over my head. "Well," he said. "I guess you could include the black market in used x-ray film." He turned to walk away. "DON'T move your head," he called out behind him.

As soon as I heard the buzzing noise that let me know the x-ray had been taken I, of course, turned my head. "Black market in x-ray film? They sell it?"

"Yep." He said.

"To whom?"

He shrugged his shoulders. "That's about all I know Doc."

"But who do they sell it to and why?"

"I told you. I don't know. I don't get into that kind of thing myself, or listen to people talk about it." He walked away again. "DON'T move your head."

I could hardly wait to get home, and of course, as soon as I did, I was on the telephone to the Florida Department of Law Enforcement, a veritable treasure chest of information. I phoned my most interesting source.

"Randy?" I said. "You know anything about a black market in x-ray film? Um, sorry, it's Christina Johns."

"I kinda figured that." He laughed and thought for a moment. "You know, I don't, but I'll get back to you."

I loved phoning this man. He was always helpful. And, he got back to you when he said he would. In this day and age, that's just about a miracle.

A day later, Desolai phoned. He said he couldn't find anything, but he did have a suggestion about who to call. You got to love this guy.

Within a few minutes I was dialing the telephone number of John Grow, a retired Detective Sergeant from the Baltimore Police Department, and head of the National Association of Bunko Investigators, Inc.

Grow knew exactly what I was talking about. "Oh yeah," he said. "Years ago, the Hunt brothers bought up all the silver on the market and the price of silver went higher than it's ever been."

Characteristically, when that price of silver hit the ceiling during the seventies, the criminal entrepreneurs were there, waiting to take advantage of the situation.

"There's a chemical process to get silver out of the film." Grow told me.

According to Grow, there were two primary ways criminals got their hands on the x-ray film silver. First, they took the tried-and-true, easy route, they just stole it, sometimes, netting $20,000 to $50,000 of silver in one heist. The second method was more artful, and as Grow told me frequently pulled off by ethnic Gypsies. Individuals would appear at x-ray labs, posing as Native Americans. They would tell heart-rending stories about the impoverishment of their tribes, and tell the lab owners they wanted to use the silver to make trinkets for tourists.

Believe it or not, the scam worked over and over again. During the seventies, according to Grow, this scam was a problem all over the country.

Even though the scams and the heists are not seen very often now because the price of silver has gone back down, I thought this was fascinating.

I never even knew x-ray film contained silver, much less that there was a countrywide crime problem with thefts and swindles of film during the seventies.

In my classes, I use this story as yet another example of the opportunistic nature of crime and criminal organizations and the way in which they are always on the lookout for new scams.

The economy changes, a certain commodity becomes profitable, and you can bet your bottom dollar that organizational crime will be into it like a rat up a drainpipe. Makes you wonder if they all read the Wall Street Journal.