I've been running a Dark Heresy campaign for five sessions and, while my players have enjoyed the setting and stories, they have found that the basic skills do not offer enough investigative tools for them to find their own leads. While I've allowed them to roleplay some crime scene analysis, I think they'd benefit from some rules-based skills. Do you recommend The Book of Judgement for opening up the investigative side of Dark Heresy campaigns? Is there an online source for houserules in this area? How do you run investigative components of pre-written modules (such as 'Edge of Darkness' and 'Rejoice For You Are True')?

they have found that the basic skills do not offer enough investigative tools for them to find their own leads.

What are they wanting to do that the rules don't support? If it's a case of skills they don't have, consider using contacts or services to let them call in some assistance from an Arbites Verispex team (which is apparently the formal name for what you might call 'CSI Sibellus'. Sunglasses optional).

Book of judgement is useful but doesn't explicitely provide new skills.

Broadly speaking, to my mind:

Search: Find things 'out of place' in an area you're specifically looking in.

Awareness: Spot something 'out of place' when not specifically looking or outside the area you expect to see it.

Scrutiny: Judgement of something when analysing it closely - spoting fakes, planted evidence, identifying marks, etc.

Evaluate: Identifying something, assuming it is what it looks like. Scrutiny + Evaluate between them would cover most 'general forensic work'.

Medicae: General autopsy work.

Scholastic Lore: Pretty much any might be relevant, but Chymistry is probably most vital for 'bloody handprint' work. Bureacracy lets you track someone's accounts or public vox records, whilst Heraldry might help place something that belongs to a corporation or noble house.

Common Lore: Tech to identify equipment. Faction-specific lores (mechanicus, ecclesiarchy, etc) as required. Ditto forbidden lores.

Trade: Trade (armourer) is building and maintaining weapons but might also be called upon to identify them, given a bullet or ejected cartridge casing.

For investigations, I tend to figure out X number of 'key clues' (ideally more than the minimum number required) and where they are, then Y number of 'connecting places' that may or may not hold minor clues, drop the players somewhere on the map and let them decide where to go (possibly with one or more hints to minor or major clues in hand). Edge of darkness does this and it works very well; it's one of my favourite adventures.

Book of judgement has a much more linear 'investigation mechanic' for pre-generating missions, which I must admit I haven't tried. I'd use it to generate ideas, but probably not run an investigation straight off it. Remember, don't try and be too linear in planning a mission, especially one where the players are specifically being made to think - because if you have a nicely planned out linear route, expect them to hang a hard left and head off away from your pre-planned story at a disconcerting rate at the First. Bloody. Possible. Opportunity.

Trust me on this.

Thanks for the reply, very helpful indeed! The issue arose as a problem in 'Rejoice For You Are True!', when the clues dry up and they have to relocate to Ambulon. I wanted to be able to suggest rolls when they were attempting to figure out leads of their own to avoid them feeling that they were being railroaded (this is the first campaign I've ever run). Your post has certainly helped with that. I'm getting better at adlibbing, but if you have any suggestions for how to come up with possible clues in an adventure that would lead them in the right direction should they miss the clue written into the scenario, that would be great. I'm definitely in favour of the sand-box approach to missions and thought that 'Edge of Darkness' gave them much more freedom. Luckily, the Haarlock's Legacy trilogy looks as though it favours this approach, which is what we're entering into next. I've misplaced the list, but I think I picked:

'Edge of Darkness'

'Rejoice For You Are True!'

'Damned Cities'
'Shades on Twilight'
'Tattered Fates'
'The House of Dust and Ash'
'Dead Stars'

Do you recommend the Book of Judgement for fleshing out some of the law enforcement protocol? One of my players is an Arbitrator, so I'd like to help him out with the sort of knowledge his character should have.

Your post has certainly helped with that.

Thanks!

The issue arose as a problem in 'Rejoice For You Are True!', when the clues dry up and they have to relocate to Ambulon. I wanted to be able to suggest rolls when they were attempting to figure out leads of their own to avoid them feeling that they were being railroaded (this is the first campaign I've ever run).

There are five real options for 'guiding' the players when they haven't got a clue (literally) - picking the right one is a matter of judgment of the players, the situation, and not doing the same thing too repetatively.

Optione Ye Firste: Do Nothing

Exactly as it sounds. They miss the clues that suggest shennanigans are occuring in Ambulon. The bad guys get away. Vaarak gives them a severe dressing-down, but at least thanks them for saving his friend. Investigations into the choir are carried on by others, and the results mentioned in further meetings with the inquisitor. If they are genuinely stuck for ideas, then nothing happens, strike it as a failure and move it on to the next mission.

Option Ye Seconde: Helpful Advice

An NPC walking past the area going "Why look! What a blatantly obvious clue! I wonder how that got there!" is an extreme response and one that you (quite rightly) want to avoid using too much. That said, in extremes, it can be the only option. It can also be used to help reinforce certain characters personalities; after all, they have skills your characters don't. Taking the end of the Sibellus section of Rejoice For You Are True as an example, post mercenaries applying explosions to things, you might 'cut' to a scene at the Templum Mori, with Medicae-Interrogator Sand poking the bodies and debris from the residence, and providing them with information as to who they are and where they may have come from. 'Specialists In The Basement' like Sand (think of him as Scintilla's version of David McCallum/Pauly Perette) don't undermine the players too much, because they don't work in the field - you bring something important to them, and let them give you the details you can't extract without their skills.

Option Ye Thirde: Rewrite The Universe

Nothing in the story really requires the second act to take place in Ambulon. That other site could just as easily be in Sibellus. Ask the players what they want to do and why, and - as soon as they head to somewhere which logically could contain the site, it will . The illusion of choice is a basic GM trick as long as the players don't realise you're using it; let them chose freely between door A and door B, without realising that Room C is behind both of them. Again, be careful not to overuse it!

Option Ye Fourthe: Sudden Inspiration

Just as an Awareness test is grounds for pointing out that someone is aiming a gun at you, a Logic or Total Recall test, or similar, is grounds for pointing out a key fact or connection that the players may have missed. It's also worth noting that most players cotton on to this a bit - failing a logic test and not getting any information is a shame but (trying to out-think the GM) they will go "A-hah! I had to make a logic test whilst talking about the building the assassin leapt from - clearly there is something significant about it. Maybe we shall look at what we know about it in more detail..."

Nothing of course requires that to actually be the case - and occasional awareness tests where no actual threat exists is a great way to induce paranoia in your players, by the way - but it's a nice way to yell "HEY STUPID! IMPORTANT PLOT POINT HERE!" without handing the clue over 'without a fight', as it were. The players should, wherever possible, feel that either their own brainpower or their character's Int and skills were responsible for them getting the clues they need.

Option Ye Fifthe: Talk To Them

The most important. One key trick I've always found is rationing time in a game session. In my experience (and this will vary wildly depending on the number of players, how early a session starts and how late they're prepared to play), an evening session covers three primary 'scenes' - and hence I plan those out reasonably well. At the end of the evening, I have a quick talk to the players to get an idea of what their intentions are (roughly) to do next - that gives me a week to figure out what the hell I'm going to do after they drove an Emperor -class battleship through the plot-hole I didn't see, draw 100% innacurate conclusions, shot the most important witness and last saw my intended storyline as it went whooshing over the distant horizon...

Equally, when the story says the 'leads have gone dead' say to the players 'how do you think you want to pick up their trail?'. Offer and take suggestions in an open manner, and then go away and figure out how to play through those suggestions as a session. No trail ever goes completely cold without killing an awful lot of people...

For examples:

Book of Judgement is a nice sourcebook for an Arbitrator - amongst other things, it describes how the various 'tiers' of precincts are organised, and several names and backgrounds of the senior officers (Such as Goremann, who's the senior Arbites in the sector).

It also has a list of what are local and imperial crimes*, and adds several useful bits of kit. Be warned that the Arbites weapons and armour are very scary and he probably won't have access to them easily when on detached inquisitorial work (not to say he can't or shouldn't but as GM you should understand these are the equivalent of SWAT gear - walking down the street in them will draw a LOT of attention).

I don't know if that list is intended to be in order, but if it is, you might want to check it; the Haarlock trilogy is Fates/Cities/Stars.

House of Dust and Ash can come at any point, but first is best.

Definitely agree with leading the whole campaign with Edge of Darkness. It may be standalone, but it's really awesome.

* Examples:

" Unsanctioned Massacres"

"Heresy"

"Intent to Commit Heresy"

"Suspected Intent to Commit Heresy"

"Failure To Avoid Suspicion"

Isn't the Imperium a nice place...