This teacher's pet would probably score well on the "Psychopathy Checklist," a diagnostic tool developed by Dr. Robert D. Hare and his colleagues. In Without Conscience, Hare, a Vancouver psychologist, lists key psychopathic symptoms, warning that we should not use them to diagnose others (or ourselves). But since everyone has met boundlessly selfish people, playing the game of psychopath -spotting is nearly irresistible. In any case, waiting for the expert opinion of someone like Hare would not help You decide whether to help a limping stranger across the street. Playing on pity was one of many roles exploited by the huggable Ted Bundy, one-time help-line counsellor, later executed for a long string of ferocious slayings.

Call them irresponsible, yes, they're unreliable, throw in undependable, too, psychopaths often don't seem psychopathic at first sight and sound. Their unshifting self-regard, shallow emotions, and utter remorselessness arc often concealed behind a shimmering veil of plausibility and resourceful deceit.

To hear Hare tell it, there may be as many as two to three million psychopaths in North America, accounting for more than 50 per cent of the serious crimes committed. Which is enough to keep anyone from aiding a motorist whose car has broken down, much less making the rounds on Hallowe'en.

More good news. The product less of nurture than of nature, psychopaths are in Hare's view legally sane and largely untreatable, at least through standard psychotherapy. A psychopath says: I'm okay, you're not. And they can come young, as in William March's novel The Bad Seed -- one of Hare's favourite examples. If sister beats baby brother's head against the wall, it may he something besides sibling rivalry.

Hare does point out that not all, or even most, psychopaths are in it for torture, rape, or murder. They may simply want to extract your life savings, sell you a nonexistent house, or borrow your body for a while. And for all his scaremongering, unsubstantiated statistics, and over-reliance on novelistic or filmic examples, Hare does have useful comments to make about psychopathic language. Possibly because their brains are wired differently, psychopaths often have no grasp of narrative structure. Examined carefully, their discourse may be rife with contradictions, even malapropisms: Clifford Olson, Canada's favourite serial killer, "was determined not to be an 'escape goat' no matter what the 'migrating' facts."

Having fatally shot himself in the Course of a police pursuit, Jonathan Yeo was no escaped goat -- and possibly no psychopath. The deviant career of the Hamilton steelworker and martied father of four encompassed the assault or rape of eight women before culminating in 1991 in the Murders of Nina de Villiers and Karen Marquis.

With commendable restraint, the journalist Kevin Marron recounts some grotesque ironies in Fatal Mistakes. Nina de Villiers's family, white, liberal South Africans, had immigrated to Canada to escape rising violence, only to have their 20- year-old daughter fall victim to a Black. De Villiers, talented, protected, adored, had sung in a video, "Give Us Back the Night" (produced in response to the massacre of 14 Montreal women by Marc Lepine in 1989), then fatally encountered Yeo at night while jogging on the ostensibly safe grounds of a racquet club in Burlington, Ontario.

There were two aftermaths. A 44-day coroner's inquest into Yeo's death came Lip with more than a hundred recommendations, many of them stemming from what seems to have been the klutziness, doziness, and chronic confusion of the Hamilton-Wentworth Regional Police. And Priscilla de Villiers, Nina's mother, started CAVEAT (Citizens Against Violence Advocating its Termination Everywhere), a national initiative that gathered 1.4-million signatures on a petition to the federal government and urged, among other things, that parole for violent offenders he tightened.

Yeo, however, had never served time in prison: his bewildered family usually protected him, and his traumatized victims often failed to come forward, or delayed doing so. Disgustingly, a "counsellor" at the Hamilton Sexual Assault Victim Centre warned one of Yeo's victims his wife's cousin -- that if she went to the authorities she Could expect intimidation and little protection from the Police and Courts. However ham handed the law may be, it can hardly he blamed for not responding to crimes it knows nothing about.

Was Yeo a psychopath' Impulsive and hungry for violent excitement, deceitful and manipulative, good at feigning mental illness when it suited him -- one can tick off Robert Hare's check-list. But Yeo apparently lacked one vital element: remorselessness. With his dead body was found a note in which he called himself "Mr. Dirt." No self-respecting psychopath would say that.