The newspaper ads for "He Knows You're Alone" and "Schizoid" are almost identical, the dominant motif being a dark silhouette with a sharp weapon (knife in one case, scissors in the other) gripped in its fist. The copy also overlaps: "The wedding night killer is about to strike again!" contrasts with "Dear Julie: Don't let me do it again . . ."

Obviously a similar MO. And at the theater where I sampled "Schizoid" over the weekend, lobby posters for the upcoming "Terror Train" and returning "Prom Night" quadrupled the stabbing imagery.

Despite the impression of bloodthirsty uniformity, these movies have been far more distinctive in mood and technique than, for example, porn features or the genre of raunchy farces spawned in the wake of "National Lampoon's Animal House," More often than not, murder thrillers exhibit an authentic flair and gusto, suggesting that they supply the least expensive and most reliable pretext for aspiring talent.

If John Carpenter could earn a reputation as an exciting young stylist with a scare movie as elementary and ponderous as "Halloween," then the unknown directors of "He Knows You're Alone" and "Schizoid" -- Armand Mastroianni and David Paulsen respectively -- merit instant cult acclaim and multiple-picture deals. They imprint a surprising amount of kicky, insinuating stuff on the screen, notably and aptitude for erotic comedy that needs a less frightening and under handed pretext to evolve in a consistently satisfying way.

It's curious that in both movies, the most shocking elements tend to receive the most derivative, cliched depiction, with the camera crudely stalking the victims while the sound track redundantly breathes down their necks. The directors can't afford to skip the violent pay-offs, of course, but they seem far more inventive and relaxed with the expository material that precedes and follows the atrocities.

In "He Knows You're Alone" the killer is identified relatively soon as a psycho whose specialty is terrorizing young women about to be married. Judging from the pile of victims he leaves behind, the homicidal urge is easily transferred to friends, acquaintances and by-standers. (In fact, a title like "He's All Over the Place" would be more appropriate.) I wish Mastroianni (a cousin of the famous Marcello but born and raised in New York) and screenwriter Scott Parker had used one of the lines echoed with creepy effectiveness in the course of their playful, verbally witty script: "Is Anybody There?"

"He Knows You're Alone" is the classier production and superior fright spectacle of the two. It opens with a deceptive, illusion-meet-reality murder sequence that combines hilarious and terrifying effects. Making a scintillating feature directing debut at the age of 30, Mastroianni reveals a special knack for juxtaposing funny and frightening stimuli, recalling De Plama and Steven Spielberg at their most provocatively amusing.

It's a safe bet that Mastroianni's cirriculum included "Carrie" and "Jaws" as well as "Psycho," which is casually discussed by one of the characters and twice emulated. "He Knows You're Alone" inspires sustained, high-decibel shrieking when Mastroianni cuts loose, but it ingratiates itself in a more congenial way by being so mischievosly movie-crazy and by swift strokes of characterizationand funny romatic by play.

Most of the characters -- including those seen or heard only momentarily -- create distinctive impressions. The apparent ease with which Mastroianni can achieve a humorous, diverse social atmosphere may carry him much further in the long run than the mechanics of pictorial terror, proficient as he is at souping up the jolts and shivers The menace seems more menacing because you're often charmed or tickled by the people in harm's way, notably Don scardino (the only recognizable human in "Cruising" not so long ago) as the affable ex-boyfriend of the imperiled heroine (caitlin O'Heany, effectively vulnerabvle in appearance but not quite adequate histrionically); Patty Pease as the heroine's liveliest pal, a sexpot with an infectiously brazen sense of humor; and Joseph Leon as the crusty, cigar-puffing proprietor of a bridal shop.

Mastroianni's exuberant talent doesn't necessarily save him from bad judgement. The killer seems to come and go with the freedom of a phantom and strike with the inhuman force of jaws or The Thing. A subplot involving a cop obessively pursuing the killer seems as misplaced as a dangling shirttail. If Mastroianni and Parker couldn't get it tucked in, they should have cut it off. Worst of all, the fadeout evocation of "Halloween" is a very dumb joke. o

"Schizoid" is a hapless title, and for the first reel or so it appears unlikely that the film will rise above its initial lurid homicide and low-budget veneer.

Neverthless, Paulsen succeeds in sustaining a mystery plot and showing flashes of intuitive directing ability in a ramshackle context. The hit in his movie consists of five women introduced sharing gossip and champagne in a hot tub. (Obvious overlooked title: "The Hot Tub Murders.") It's disclosed that the victims have something else in common: an ambiguously tormented group therapist played by Klaus Kinski, revealed to be romantically entangled with more than one female member of the group.

Perhaps the funniest line in the script occurs when murder has taken a toll of Kinski's patients, and he exclaims "Where is everybody?" (another swell title wasted) at a small turnout. The ultimate target is Mariana Hill, who writes a newspaper advice column, "Dear Julie." It's Julie's friends who get knocked off first, and the suspects are somehow connected with Julie.

At first every suspicion points rather too directly at Kinski. The rival suspects -- Craig Wasson as Julie's estranged husband and Christopher lloyd as a building suprintendent infatuated with Julie (hilariously, he's also a member of her group) -- don't receive nearly as much suggestive footage. Unexpectedly, Paulsen compensates for this weakness by springing a fourth suspect, who could be in a unique position to frame Kinski. s

Finally, in a deft climactic manuever Paulsen gets all four suspects and the heroine in the same deathrap -- her office -- at the same time. Having achieved this social coup, Paulsen begins cooking with a skill you couldn't have anticipated in the early reels. Throughout the denouement the suspense intensifies partly through the manipulation of clever ironic details like the timely use of the prevailing murder weapon, a pair of scissors, to help save the heroine's skin. When the final credits roll up you still feel slightly breathless from the whirlwind payoff.

Mastroianni and Paulsen haven't come to town with the most reputable vehicles ever made, but you leave convinced that they know how to get some exciting mileage out of those rattletraps.