Police Say They Are Unlikely to Catch Phony Ransom Caller : Investigations: Threats apparently are random and never made to the same woman twice. Law officials and phone company lack the technology to stop them.

Unless the man who has been harassing San Gabriel Valley women with threatening telephone calls changes his method of operation or reveals his crimes to an acquaintance, police say there is little chance of catching him.

Since April, more than 50 women from Pasadena to West Covina have been called by the man, who says he is holding the woman’s husband hostage at gunpoint and demands ransom money for his release. The caller, who has an East Coast accent, also insists that victims call him “sir,” and frequently asks the women sexually explicit questions.

No husband has actually been held hostage, and police said no one has paid the caller any ransom money. In most cases, the women called their husbands to make sure they were safe before contacting police.

Officers from 10 San Gabriel Valley law enforcement agencies are investigating the calls, which have increased in frequency during the last month. But because the man picks his victims seemingly at random and has never called the same woman twice, investigators say he is virtually unstoppable.

“He could probably get away with this forever,” Monrovia Police Sgt. Ron Buck said.

In investigating obscene or harassing telephone calls, Buck said, the standard approach is for police to set an electronic “trap” on the victim’s telephone line. Once installed by the telephone company, the trap traces all incoming calls.

Although one recent victim had a trap installed, the man has not called back, Buck said.

In some states, telephone companies offer customers a caller-identification service. This allows people to see the telephone numbers of calls coming into their homes or businesses and has led to dramatic drops in reports of obscene and harassing phone calls, Pac Bell spokeswoman Kathleen Flynn said. Similar service will be available in California in mid-1991, she said.

Pasadena Police Detective Dennis Edwards said such a system would make investigating this case easier. “It would help immensely, and I’m sure it’d cut down on the number of annoying phone calls that would occur” in general, he said.

Without benefit of an incriminating telephone number, investigators have looked for a pattern to the calls in hopes of uncovering a suspect.

Sgt. Tom More of the sheriff’s Temple City substation said that data has been informally exchanged between the 10 law enforcement agencies investigating the calls.

By pooling data, authorities found that the caller picks couples listed jointly in the phone book, and he calls the home on weekday mornings after the husband would presumably have left for work. But that has not led authorities any closer to a suspect, More said.

Investigators said they are looking for suspects among people with histories of making obscene or harassing calls. Although this approach has supplied a number of names, the law does not permit authorities to request phone bills or take other action without evidence that would make someone a clear suspect in the case, Pasadena Police Sgt. Monte Yancey said.

“So we proved that (a hypothetical suspect) was in Culver City at the same time someone in Culver City was called. Then we’re supposed to prove beyond a shadow of a doubt that he did it? It’s not going to happen,” Yancey said.

Yancey and other law enforcement officials said the best chance of catching the caller is a tip from the public.

“There’s no amount of (police) manpower in the world that can help you in a case like this,” Yancey said.

But as the crimes are publicized, he said that someone to whom the caller may have revealed his actions may come forward.

Sheriff’s Lt. Phil Bullington, who is working with More on the case, agreed that publicity may help ferret out the culprit.

“As they get a lot of publicity, they can’t help telling somebody, ‘Hey, that’s me,’ ” Bullington said of many criminals. “That is something that gets a lot of people caught.”