How about The Lost Files of Sherlock Holmes?

Another perhaps more obscure detective adventure is Return of the Phantom: https://www.mobygames.com/game/return-of-the-phantom

The DOS versions of the Tex Murphy games .
I think they are available on gog.com

https://en.wikipedia.org/wiki/Tex_Murphy

Jack Orlando: A Cinematic Adventure
Gabriel Knight: Sins of the Fathers -- very much an investigative type adventure; the protagonist is not a police/private detective, but it'd be a shame to overlook it for that reason.

by that, then Colonel's Bequest and Dagger of Amon Ra

Maybe Sam & Max Hit the Road

Police Quest series?

Broken Sword to some extent.

Blade Runner (1997)?

ETA: No, this is a Windows game.

The 11th Hour?

darry wrote on 2020-09-26, 04:55:

The DOS versions of the Tex Murphy games .
I think they are available on gog.com

https://en.wikipedia.org/wiki/Tex_Murphy

YES!

Under a Killing Moon and Pandora Directive in particular

leileilol wrote on 2020-09-26, 05:55:

Maybe Sam & Max Hit the Road

freelance police, ma'am

Not really has a detective as a protagonist, but the Last Half of Darkness also is a mystery game.
Re: Covox speech thingy!!!

I also know of two or three more investigative games for DOS,
but they are in German only, sadly.
One has a journalist/reporter as protagonist, I recall.

Edit: Does Alone in the Dark also fit?

Efit: Now that I think of it, Rise of the Dragon and Snatchers may fit.
The latter one is for PC-98 or MSX/PC-88 and Sega CD, though..

Deja Vu 1 & 2

If you want to go really retro,

Snooper Troops by Spinnaker
the Carmen Sandiego games (Broderbund, I think)

...and maybe Agent USA could be put into the "detective" category (although intended to teach US geography). These are mostly children's games. Snooper Troops is a bona-fide detective/mystery game that I think an adult would like also. (You'll need a way to slow down the system for Snooper Troops or you'll be constantly wrecking your car).

newtmonkey wrote on 2020-09-26, 04:12:

Another perhaps more obscure detective adventure is Return of the Phantom: https://www.mobygames.com/game/return-of-the-phantom

entertaining game with a talkie version, but dont bother playing the last part without a walkthrough or enjoy hours/days of getting lost in hallways. i didnt care for the puzzles but the art was nice and the music good too. i would have avoided this, but i only tried it out as it had "opera" in the title, using it to test out a few sound cards and then decided it was good enough to play through. i can see why some people would not like it. worth checking out tho.

a detective game in the same style of carmen sandiego i reccomend to any 12 year old is Eagle Eye Mysteries, some kids start a detective business instead of washing cars or mowing lawns. you gotta figure out a series of whodunnit mysteries by talking to people and getting clues from various locations etc. not a true adventure game but was fun to me back in the day. there's a sequel/spinoff where its in london instead of america.

Cruise for a Corpse, you know he's a good detective, just look at the curly moustache!

The Case of the Cautious Condor, NYPD Detective.

Murder on the Zinderneuf?