She's lying in the middle of a deserted alleyway, naked as the day she was born. A blood-soaked silk stocking lies nearby, and her neck shows signs of trauma, but for now it's impossible to tell if this was the weapon that ended her life. Her face is a mess of blood and lacerations, and similar mutilations elsewhere have left her pale skin stained with red. Across her torso, a message scrawled in lipstick: "Kiss the Blood. BD."

Her name was Antonia Maldonado. She was 21 years old.

As desensitised as I am after years of video game violence, there's something deeply affecting about the crime scene before me. This is a medium often criticised for its supposed glorification of brutality, but there's nothing celebratory about Antonia's fate. True, the horrific details of her death appeal to our morbid curiosity, but where a typical horror film would drench the scene in theatrical shadow, here the body is lying in stark daylight. No, there's no glory here. If anything, it's just sad.

In any case, there's no time to be getting queasy or emotional. Somewhere out there in Team Bondi's recreation of 1947 Los Angeles, the killer is hiding - and Detective Cole Phelps is the man to find him. The area surrounding the body is littered with things that might be vital clues, or simply everyday detritus. Could that discarded coffee cup point to the murder? It seems unlikely, but it can't be ruled out. To uncover the path to the truth, Phelps and I will have to inspect every one of these potential hints. All the pieces matter.

Thankfully I already have a fairly good idea of how to approach a crime scene, as poor Antonia is actually the second corpse I've seen in today's play-test. The first unfortunate I saw was the victim in the Red Lipstick Murder, another young woman left naked, mutilated and daubed with a creepy message. You'd be forgiven for assuming that the same person might be responsible for both killings, but unfortunately the situation isn't so straightforward. The whole of LA is in a state of media-fuelled hysteria following the Black Dahlia killing (a real-life case, if you didn't know), and so there's a strong possibility that people could simply be copying the modus operandi to mask their own guilt - hence, perhaps, the reference to "BD".

In the Red Lipstick Murder demonstration, a Rockstar representative showed me how to dissect a crime scene. Now for the Silk Stocking case I am allowed to give it a whirl for myself, carefully using the game's subtle audio cues to find clues surrounding the late Miss Maldonado. As I briefly described in my first preview, there's a distinctive bit of sleuth-y music that kicks in whenever you're gathering clues from a crime scene, and a brief piano sting plays when you approach an item of interest in the environment. After single-button tap Phelps will duck down and inspect the object in question, and the left stick then allows you to turn and manipulate it in his hands. If you turn the item to an angle that reveals something important, the controller will vibrate; maintain this "sweet spot" and the camera will zoom in, prompting further inspection from Phelps.

You're not entirely alone in this hunt for clues. As long as the music is playing you'll know that there are still things to find at a crime scene, and if you get really stuck there's an optional in-game hint system. Aside from the technical aids, Phelps can also rely upon his partner - who for this case takes the form of the gruff and rather sardonic Rusty Galloway. Mr Galloway doesn't seem to like Phelps very much, but he still pitches in at the scene, calling you over to clues you may have missed. You can also force the grumpy git to drive you about town, if you're in the mood for a trip skip.

As with my first preview of L.A. Noire, I'm reluctant to go into too much detail about the way the Silk Stocking murder pans out, as to be too explicit would be to deprive you of many of the surprises and twists that make the game what it is. What I will say is that the initial crime scene soon reveals itself to be a lot larger and more complicated than what initially seems to be, and while the small library of clues certainly give our homicide detectives a lot to work with, there's also a sense that the killer may be toying with them, even telling them where to go next.

Despite such clear machinations, Rusty is convinced that the culprit will turn out to be Antonia's husband. Then again, Rusty doesn't seem that bothered about doing the job thoroughly. Corruption is rife in post-war Los Angeles, and you get the impression that Rusty wouldn't be above framing someone for the sake of an easy life. The funny thing is this crooked appearance doesn't make him any less likeable. Rusty resents Phelps for his swift promotion to Homicide (the third of the game's five desks), but his disaffected attitude and cynical banter provides the case with a grimly amusing backbone.

The middle part of the case finds Phelps and his partner moving through a string of run-down locations, interrogating the locals and uncovering new leads at each stop. The first port of call is a battered old boarding house where the victim used to live, but the investigation carries the pair to an apartment block, a grubby bar and a slightly shifty-looking fruit market, as well as to the LAPD HQ. While the investigative aspects have some overlaps with the Phoenix Wright games - in a very loose sense, obviously - it's pleasing to note that the progression of the case feels organic, and comparatively non-linear. In my hands-on, a successful interview at the guesthouse tips me off to the existence of the aforementioned bar; had I missed this I might have been alerted by a matchbook that can be found in the flat belonging to Antonia's estranged husband. Obviously the case will always conclude the same way, but the exact route taken to get there will vary from player to player.

The conversations with suspects and witnesses unfold as I described last time, forcing you to pay attention to your interview subject, and then choosing how Phelps responds: with belief, with doubt, or by flat-out accusing them of lying. Once again Noire's MotionScan technology steps into the limelight, as the focus turns to the game's eerily realistic digital faces. After my first preview I was a little concerned that Team Bondi's virtual actors might be overly reliant on obvious cues to signify that they were lying, but happily this doesn't appear to be the case. Perhaps I just need more practice - or perhaps I'm just an emotional cripple - but there were quite a number of times when I pick the wrong response during an interview. At one point this results in Phelps needlessly savaging Ms. Lapenti, the guesthouse landlady - referring to her as a "nosy old hag".

To my great pleasure this slip-up is subsequently referred to twice by Galloway - once as we leave the house, and then again shortly after we speak to a snooping resident at the apartment block elsewhere. It's callbacks like this that turn Noire's characters into believable creations, and it's clear that significant effort has been put into giving the shifty cast a life beyond their lifelike outer appearance.

It's also encouraging to note that the whole Silk Stocking Murder case, which takes the best part of an hour to work through, is almost entirely based around detective work. Sure, there's was a brief fist-fight, and a car chase as the demo reaches its close, but for the most part the action consists of chatter and thoughtful investigation. It takes confidence to take this kind of design approach, especially if this kind of balance is typical for the game as a whole. The punch-up sequence uses fairly simple block/counterpunch mechanics, in a manner not too dissimilar to last year's Mafia II; the fight served its purpose as a brief change of pace, but its mechanical qualities still clash somewhat with the graceful presentation found elsewhere. For me, the car chase works far better. Vehicle handling is more fluid than the model used by GTA IV, but the cars themselves still move with a definite sense of weight - especially when you're trying to manoeuvre through traffic in pursuit of a fleeing suspect.

The Silk Stocking case closes with the arrest of the apparent killer, but it's clear that the investigation has raised as many questions as it has solved - for Phelps at least, if not for his dubious partner. The similarities with the prior Red Lipstick Murder suggest sinister machinations that extend far beyond the death of poor Antonia Maldonado, but for now the ultimate truth will have to wait. Once again I am left hugely impressed by Team Bondi's work, and while I have questions of my own - how does the gunplay feel? And is Phelps really as clean-cut as he appears? - I'm certainly looking forward to the eventual answers. And with a release date set for May 20, this hopefully won't be The Long Goodbye.

L.A. Noire will be released on May 20 on PS3 and Xbox 360.