In SWAT 4, towards the end of the SP campaign, the mission, "Children of Taronne Tenement", revealed what the cult did to the children of their members. The foreshadowing was blunt and obvious, but even if you perfectly complete the mission parameters, SWAT still "fails" by SWAT merely showing up. To tell the player the only way to win is to not play takes some stones and Irrational pulled it off with this mission.

For me, one of the most underrated and enjoyable criminal case adventures is the Post Mortem/Still Life series. My personal favourites are:

Post Mortem (https://www.gog.com/game/post_mortem) and the first Still Life (https://www.gog.com/game/still_life) with Gustav as main protagonist. One fine told story and nice puzzles in a good presentation.

Well, for me I think is the case in Pandora Directive (the fourth Tex Murphy game). I don't know about Disco Elysium, but I will found if a win a copy!

People don't traditionally think of Arcanum: Of Steamworks and Magick Obscura in terms of a mystery; but it's all laid out for you from the very first cutscene: why was the airship you were aboard gunned down in cold blood, who was the strange gnome who charged you with his dying breath to "find the boy", and who and where is the boy of which he spoke?

The answer will take you to every corner of the continent, as you unlock clues towards a conspiracy thousands of years in the making, involving powers and personages you never knew existed, on a scale you never imagined! Compared to that, "Who shot the dame's husband?" isn't even in the same ballpark.

The most memorable criminal case you ever solved in a video game?

Chase H.Q (late 80s), Amiga - criminals catched, case solved.

Broken Sword 3! My first foray into pncs and mystery adventure games!

I'm not good at remembering these kinds of details for past games, but there is one I recall since I replayed it not too long ago.

The Witcher - Anatomy of a Crime

There were so many ways it could be solved and the first time I reached the end of the quest I was surprised by who the villain turned out to be. Though I did have some clues along the way, just not a clear enough picture during that first playthrough.

The solution was less than ideal the first time around compared to the second. But the replay was spaced out long enough to enjoy the quest again. :)
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Surprisingly a Baldur`s Gate 2 in Bridge District,.a case "Solve the "skinner" murders in the Bridge District".
I still remember the smell of the tannins ...

Ze bombing and murders in Broken Zword 1.

In Gemini rue. I was investigating where my missing brother was and I found out who I really was. It was an incredible twist in the plot.

I will say my favourite Sherlock Holmes game: The Case Of The Serrated Scalpel.

Quite a few cases come to mind, but maybe the most memorable was Persona 4's, simply because you just don't expect a kind of dating sim jrpg to be about catching a serial killer, and doing it while being the most light hearted game in the whole series (yes, serial killing is extremely light by Persona's standards, and even lighter by SMT's). And despite this, the mystery is still complicated but solvable, and you actually have to solve it to get any ending except the worst (and to get best, you have to go the extra mile, solving an even deeper mystery, to which very few things even point you to know about it existing). So yes, solving mysteries with the power of your true self, while learning more about the powers of friendship is quite hard to beat in memorability, at least for me.

Witcher 3, finding the real criminal/killer in Novigrad...

Detective mystery always a favourite genre of mine. But recently i'm into visual novel, currently my favourite case is the entire The 25th Ward: The Silver Case premise right from the get-go.

There are 2 equally memorable ones:

1. 'Her Story': The mechanics of 'Her Story' may be simple, but piecing the fragments of the interview to reveal the truth (or is it?) was challenging and required careful thinking and organizaion. In the end, the reward of finding out what happened (and how you interpret it) is all yours, not the game telling you what to search for and putting it all together for you.

2. The events of 'Return to the Obra Dinn'. The very little hand-holding that the game provides made me feel really empowered and rewarded every time I identified a perpetrator, victim and method. Whenever I got a part of the grander puzzle solved, I knew it's because of my knowledge, skill, and deduction (okay, perhaps a bit of luck here and there), not because the game told me what to answer. It's too bad you can only experience the full wonder of 'Return to Obra Dinn' once.