Ahh, the Sherlock conundrum -
How to make the detective work to prize out the culprit. When you’ve got a keen nose that can dissect scent as we humans might colors, what’s the bother?
It comes down to contrast. Take a sitting room of 20 assorted species in a somewhat old mansion.
Firstly, at least three will be able to hear the crime being committed anywhere in the house - bats most notably, but other species hear just as well. A host of them could obviously figure out the guilty party with just a sniff around the unfortunate victim (unless they were offed by something like a firearm - gunpowder would ruin any scent markers, but arrows and darts would carry a scent).
So then, could we carry off a closed-room scenerio in with such a cast?
Easily. A bloodhound can track one perp - but they get muddled when the guy crisscrosses their own trail, or goes into an area peopled with many of their species (dogs have absolute hell tracking in a mall, but not a private residence, golf course, or similarly low-trafficked areas). The perp could also mask their scent with things like skunk oil (which would be readily available if skunks number among the sentient species), capsicum, or the like. About as clearly as a witness watching the crime in progress would be rendered unreliable by a simple flashlight beam or very loud noise - it rattles their thought process and corrupts their recall. A perp dousing their victim with a good spritz of capsicum would all but obliterate a scent-based CSI’s olfactory observations.
The size of the cast would be of extreme importance in this instance. Six people around a seance table simply would not work (without a LOT of work on the writer’s part) because of the dearth of confusing stimuli. But one guy in a crowded theater opening up with a firearm? Good luck picking him out when everyone smells of fear, blood, and gunpowder. A crowded mall would make anything beyond visual acquisition of a target all but impossible - like humans trying to Find Waldo on a red-and-white Escher print.
The advantage here is in observation - the investigator merely has more acute senses, she does not have MORE of them (unless it’s fantasy or SciFi which grants an expanded sense pool). Like ‘Monk’ or the guy from ‘Psyche’; their investigatory prowess comes down to their ability to observe the additional minutiae their heightened senses offer. Where a human might miss the perfume or subtle musk, a canine or snake might be able to - but miss the obvious clue in a color photograph that those two species see as a low-contrast blob. Acute hearing can detect things on an audio tape more readily but can’t read the fine print label on the cassette.
And note that we humans overlook the obvious every day because we SEE IT every day; our brain filters it out. Imagine how much filtering dogs do in our own house? What they smell daily and overlook, what they hear that we cannot and learn to ignore. Non-human characters would do the same. Even the best of them might overlook the smell of a dog because they smell them everywhere, every day. Just as we miss faces in a crowd.
When it comes to detectives in a non-human genre, the strengths can believably come with drawbacks. Play to them, and that will make your story work with the Anthro, but not without them.