Another good story.
The writing is clear. I was pulled through the event nicely. I like it.
The suggestions below are just thoughts of how I might handle it, which is only for perspective or sharing only:
I might name the detective in the first sentence. Might save a "which one is John" question later in the story.
If it is not critical to the solving of the crime, I'd pick another detail beside '10 mile radius' for the second usage...like "mid-town alone" or "east of 103rd" something to add a layer in the readers sense of place.
Finding a business card is pretty convenient, especially for a serial killer erasing victims fingerprints. But, they always make mistakes. Detective John knows this..doesn't he?
Finally, 24 words is a lot. There have been rounds where I would've given a fortune in GPs for just five.
If your like me, you're never really interested in how someone else would write your story, but another writers perspective on storytelling is sometimes a different thing altogether.
Again, the story is good, and I had no problems reading, following, or enjoying it as is.
Thanks for the read.