Movie about a guy who has to kill every few years for immortality

I once watched a murder mystery movie where, if I’m rembering it correctly, someone investigating crimes realized that there was a pattern where someone was getting killed every so many years over a span of over 100 years. Eventually it was discovered that the crimes were committed by the same guy who needed to kill in order to be immortal.

Anyone know the name of this movie? I was reading a book yesterday that reminded me of this, but I was just a child when I watched it.

Thanks.

There was an x-files episode similar to that - Tooms.

That was my thought too, sure you’re not conflating them?

Have definitely seen that elsewhere.

This is definitely not going to help you find the movie you were thinking of - but was the book that reminded you American Gods, by any chance?

Is it The Night Strangler ? (second t.v. Movie in the Night Stalker series)

It’s a very well used plot–I’ve seen it on any number of science fiction TV shows. Star Trek even had a version, although the death was much slower, and a rip off of a romance novel.

The x-file episode springs to mind, IIRC he had to consume human livers. Vampires are also pretty similar if you think about it.

Sounds very much like a ripoff of Robert Bloch’s “Yours Truly, Jack the Ripper” (where is where Star Trek got the concept – Bloch wrote the script for it).

Aha, I think you may have it! This seems to match the vague memories I have of the movie. I’m going to check with my brother–he is a year older and was the one who picked the channel that day. Thanks for weighing in (along with other responses that might have yielded good cludes).