Short story: Cop chasing serial killer, both are shape shifting aliens

Question

I'm looking for the title of a short story I read years ago.

It is about a cop chasing down a serial killer but it turns out both of them are actually aliens and the cop turns into a blob and envelopes the other alien until it dies.

It was part of an anthology. I read it maybe 7 years ago but the anthology could have been much older than that. For some reason I keep thinking it was in a horror anthology as opposed to to a straight up sci-fi anthology. The story takes place on Earth and it reads like a standard cop/detective story but then you get to the end and boom you get the alien twist.

Answer 1

Dean Koontz, "Hardshell".

It's in these anthologies: "Predators" (1993), "Strange Highways" (1991), and "Night Vision 4" (1987). Two reviews on Goodreads for the Strange Highways short story mention it's about a cop and a serial killer chasing each other and that they obviously aren't quote fully human. The killer is also mentioned to be a shape shifter.

Dead men don’t bleed.

A game of cat and mouse develops in an abandoned warehouse (have you notice that in any story the warehouse always are abandoned?!) between a wounded cop and a vicious killer.

However, who is the “cat” and who is the “mouse” is still to be seen, since there are a lot beyond the evident.

_{Strange Highways review, Alejandro}

Hardshell - In a abandoned warehouse, LAPD Det. Snow is chased by immortal Karl Skagg the "Shape Changer". He learns Karl's 300+ years old. And Det. Snow could to be made immortal?

_{Strange Highways review, Fred}