Nowadays, Relationship With Mere Acquaintance Can Be Deadly : In today’s society of violence, drugs and crime, men and women alike must practice extra caution before striking up a friendship or getting closer to someone.

Though I am a member of Mystery Writers of America and have written about many fictional murders, certain true murders are extremely painful to read about.

Take for example, Kellie O’Sullivan, the Thousand Oaks nurse who was apparently abducted and killed for her car, and the San Fernando Valley slaying of Sara Weir, 19, in which a man is being sought.

In all likelihood O’Sullivan had no control over her fate. But Weir might have--at least to the degree that she chose to become acquainted with her alleged killer.

I found her story disturbing on many levels. She seemed to be a beautiful young woman on the threshold of life.

Weir met her alleged assailant, Douglas Oliver Kelly, at a health club in Burbank. He apparently impressed her enough to gain her trust because she hired him to be her trainer. No doubt it was this trust and the naivete of youth that led to her death.

Weir wasn’t the only person taken in by Kelly, who is described as a 35-year-old charmer with a quick line. At a health club, where outward appearances are paramount, people don’t tend to delve too deeply into someone’s past.

Like O’Sullivan’s slaying, Weir’s death hit close to home. She might have been anyone’s daughter, sister, friend. She might have been myself in the late ‘60s or early ‘70s, when I took chances that now seem awfully dumb.

But mine was a generation that hitched rides with strangers and crashed at the apartments of people we barely knew, since we were all brothers and sisters in the Age of Aquarius.

It was only the sordid revelations of the likes of Charles Manson and Ted Bundy that caused us to face the reality that it is best not to become too well-acquainted with some strangers.

Things have not gotten better in the past 20 years--they’ve gotten worse. Guns are more accessible; drug-crazed addicts, more desperate. Also, with the breakdown of the family and the weakening influence of religious institutions as a place in which to turn to formulate friendships, people must rely more and more on their own instincts when sizing up a stranger.

What advice would I give a young woman so she might protect herself from a predator? There are no hard rules, but here are some guidelines to keep in mind.

* Before considering getting into the car or visiting the apartment of a man you’ve just met, acquaint yourself with his circle of friends. Ideally, you should meet family members, but in our transient society that is often not feasible.

* Do his friends drink a little too much? Are they rough with their girlfriends? Do they hint to habits of his of which you were unaware--drugs, for example?

* Are there things about him that bother you more than you’re willing to admit? An off-color tattoo? His frequent use of obscenities? The bad temper he revealed when he blew up at the waiter or bartender? Small lies you’ve caught him in?

* Whether the relationship is businesslike, of a romantic nature or simply a friendship, never meet your new acquaintance anywhere but in a public place until you feel absolutely comfortable. Incidentally, this applies to people of either gender. Men can find themselves with women who turn out to be con artists or psychotics.

* Should the friendship grow, you have a right to find out from others the reason why his ex-wife left him and why his ex-boss fired him.

* Trust your instincts, but be overly cautious. It’s your life you’re gambling with!