The murder rate may be astronomical and La Cosa Nostra may be triving, but the high mucky-mucks of law enforcement in New Jersey want you to know that they're on the warpath against dangerous criminals operating in the Garden State.

With hoopla unmatched since the Lindbergh kidnapping, some hot-dog prosecutors, sheriffs, et al. in central Jersey called a press conference to announce that they had cracked a virulent outlaw band and confiscated the sordid tools of their filthy trade.

Had the law caught the guy who nailed Hoffa? Had they tracked down the mobsters on casino row? Is it safe now to walk the downtown streets at night? Not quite. No, instead of pursuing real criminals, the prosecutors had invested hundreds of man-hours preparing charges against seven high-school kids whose crime was -- are you ready? -- sending and receiving messages through computer bulletin boards.

During the press conference, at which the miscreants' Apples, TRS-80s, etc. were displayed as if they were exotica from outer space, prosecutors charged that the Silicon 7 had used their home computers to invade Pentagon security systems and -- I loved this one -- to move communication satellites around in space.

It was spectacular stuff. It was also preposterous. No kids had invaded any system, the Pentagon reported. "We have no indication that there's been any disruption or relocation of our satellites," said AT&T.

When it came time to press formal charges, the case began to look less spectacular. The delinquency charges were based on a case of "conspiracy to commit theft." The key word is "conspiracy." The prosecutors don't need to prove that the kids actually broke into the Pentagon or moved any satellites; to win a conspiracy rap, they only have to prove that the kids talked about it.

This may come as a shock to the law enforcement establishment in New Jersey, but kids have been sitting around on street corners talking like that as long as there have been street corners. The only difference in this case is that these seven kids used the 1985 version of the street corner: A computer bulletin board.

Instead of hanging out on the streets on a summer night exchanging their fantasies, kids all over the country now do their fantasizing via computer bulletin boards. So do millions of adults, for that matter. In most places, they are free to do this without harrassment from headline-hungry prosecutors.

According to The New York Times, the prosecutors reported that the youthful mob had "exchanged information through their systems on how to . . . make explosives from household chemicals. . . . "

At the risk of bringing this posse of boobs down upon me, I confess that in my teen-age years I possessed a recipe for making nitroglycerin. I got the evil information from a kid who wrote it down on a strip of paper. No prosecutor seized that kid's pencil and charged us with "conspiracy." But when the same childish transaction is carried out via computer, police sirens wail in the Jersey streets.

Shortly after their ballyhooed arrest of the Silicon 7, the prosecutors announced breathlessly that they were investigating 623 other Americans. The crime? This Gang of 623 had called the same bulletin boards the original seven liked to use.

It's a shame to burst this marvelous prosecutorial bubble, but frankly, any bulletin board with only 623 callers is a rinky-dink operation. If New Jersey's prosecutors don't have enough serious crime to keep them busy, they could start investigating some of the bulletin boards that have tens of thousands of callers.

The whole silly business amounts to a severe case of prosecutorial ignorance. In fairness to the prosecutors, though, it must be noted that they were enforcing an equally ignorant new law passed this spring by that famed repository of wisdom, the state legislature.

The legislators were trying to deal with the real, if relatively minor, law-enforcement problem of "hackers" who invade big corporate data bases that contain credit-card numbers and financial data for large numbers of people.

The effective way to stop these electronic break-ins is to make sure that banks, credit card companies, etc. maintain adequate security over their data. Any computer system can be made secure against attempts to break in. But the security measures can be expensive, and some credit firms have been reluctant to spend the money.

Did the legislature pass a law requiring these firms to establish adequate security over the records they maintain on all of us? Of course not. The legislature went after the weakest target, the target with no pin-striped lobbyists in the state capitol: the teen-aged computer buff.

A foolish law led to a foolish set of charges -- charges that should, and probably will, be dropped once the prosecutors learn something about computer bulletin boards. Do you suppose they'll call a press conference when that happens?