story identification - Old sci-fi/thriller movie centered around a pistol that causes blackouts/temporary amnesia with bursts of light

Plot Details/Summary

I saw this one on HBO as a kid in the 1980s. As best as I can remember, the plot was along these lines: There's a series of murders occurring, and the protagonist, I believe, is a suspect at one point. IIRC, he's at or near the scene of one of the murders. The protagonist can't remember what happened during the time of the murder - what he was doing, etc.

As he investigates, the protagonist discovers an experimental weapon has been developed. It's a handgun that fires pulses of light. The pattern of the light causes the victim to go in to a sort of blackout. Not really unconscious, but sort of stunned in place. When it wears off, the victim is left with a memory gap, with no recollection of what happened or what took place while he was stunned.

I recall the protagonist is able to acquire the weapon, and turns the table on the man who's been killing people with it. I don't recall how the weapon was developed, or why the man was killing people in the first place. I do remember the protagonist beats the killer up by using the weapon to stun him and then punching him out between bursts.

Timeframe

I saw the film in the early 80s, so I'd say 70's or 80s. It was a color film, and I remember it being fairly "modern"-looking - i.e. not an old 60's film or the like. That's all I can recall.

Answer

"Looker" (1981)

Here is a part of the plot summary from Wikipedia describing the gun.

During his investigation, Roberts discovers some advanced technology devices the Digital Matrix corporation is using to hypnotize consumers into buying the products they advertise. He also discovers the Light Ocular-Oriented Kinetic Emotive Responses (L.O.O.K.E.R.) gun, a light pulse device that gives the illusion of invisibility by instantly mesmerizing its victims into losing all sense of time.

This movie stars Albert Finney as a plastic surgeon who investigates when several of his female patients die mysteriously. It was written for the screen and directed by Michael Crichton, the author of Jurassic Park, and many other techno-thrillers. Here is a scene from YouTube showing a scene with the gun being used on Finney's character by the company goon.