Criminals might use them "for trailing police." Or wives might use them "to follow estranged husbands."

For these reasons, the Federal Communications Commission has proposed limiting the sale of radio tracking devices to official law enforcement agencies, not to the public.

"For nearly every beneficial application," the FCC said of the devices, "there is a nefarious one."

Wackenhut Electronics is one of several companies in the market. Five years ago, it introduced its "Blood-hound System" -- a tiny transmitter and portable tracking receiver -- and it sold well for several years. The transmitter sends out a steady, inaudible bleep that can be followed by the tracking receiver up to 2 1/2 miles away -- an easy way to keep track of someone's moving auto.

Police departments bought the "Bloodhound" and similar devices but so did private detective and a security agencies and overseas purchasers, according to Wackenhut officials. The officials said the devices are good "executive protection" as well as covert surveillance.

Two years ago, however, the Fcc declared that the radio transmitters violated the communications act and sales were stopped. Wackenhut and other companies took their devices off the domestic market and most police and federal government agencies stopped using them, while the FCC staff has been studying the problem. In January, the FCC announced its proposed rule to limit operation of the device to "police licensees."

The commission said it does not know "the extent to which [it] should enable individuals to conduct surveillance of the activities of others."

It recognized many users, such as "promoting industrial security" . . . locating a lost camper . . . reducing unauthorized use of company vehicles," are clearly in the public interest.

In the end, however, it decided that "the equipment would greatly expand the capabilities of individuals to intrude electronically into the private affairs of others, with all of the serious ramifications this would entail in the personal privacy area."

Federal courts, the FCC noted, have held in some cases that the police need a warrant in order to place a transmitter on the outside of a suspect's vehicle.

The law, "however is still in a state of flux," the FCC said. For instance, a beeper concealed in an open container does not need a warrant.

Recognizing that trucking companies and private security agencies already have FCC licenses to operate private radio networks and work with police "in matters pertaining to security of life and property," the commission gave them authority to operate tracking devices "under the authorization issued to the police department."

Beyond that, the commission concluded, "we do not think that it is desirable or in the public interest to extend this capability to other nongovernment users.c

Under FCC regulations, interested parties have until March 31 to comment and until April 30 to reply to the comments. Then the commission will decide whether to amend its proposed rule or adopt it in its present form.

Meanwhile, Wackenhut Electronics' "Bloolhound" may be back on the police beat, at least, within a few months.