CSI D&D: Creating a Forensics-Based Adventure

Table of Contents

After the success of my puzzle-based adventures with my local gaming group, using such puzzles as those found in Scrolls of Destiny I and II, I began looking around for other ways to bring in my and my players’ interests outside of gaming. Since many in our group are avid followers of the forensics shows NCIS, Criminal Minds, and the multiple CSI series, I perused the world of crime-solving to scoop some excellent ideas for our next adventure.

Keeping It Simple and Making It Work

Around the same time I began looking, one of my professor for my educational science class (basically, a class on how to teach science to kids) gave us a forensics lab that used household materials to analyze many pieces of evidence that the real scientists analyze and interpret with mass spectrometers, AFIS, and CODIS. Most of the supplies you’ll need for your own CSI D&D are already in your kitchen, around your desk, or at the dollar store.

Some things to keep in mind while running a CSI game are laws and civilian rights, whether or not the science of these techniques are proven in your world, how to prove to the local authorities that the evidence is genuine, how much magic can help in the investigation, and how to use skills to gather information and discover the techniques.

Laws and civilian rights are fully up to the DM, but just make sure that you’re not contradicting a law or right you’ve established previously. If in another scenario in this location, a PC was brought up on charges with just an accusation and no supporting evidence, then why would the magistrate ask them to investigate a crime when a local townsperson has already named a suspect without evidence? It would make more sense if a person with a vested interest in the outcome, such as the suspect, a relative of the suspect, the victim, or a relative of the victim, asked the PCs for help.

Do the people in your world understand that every fingerprint is unique? Is handwriting analysis an accepted technique? How much do the scientists in your world know about forensics? Can they estimate time of death? More importantly, do the local authorities accept and recognize the science behind the investigation? In order to make your adventure work, you need to make it obvious to the players through roleplaying with these officials what evidence is acceptable and what will be thrown out as heresy or illogical nonsense. Also something to consider: what do your players’ characters thing about all this science stuff? Mumbo jumbo, or the law of reason and reality?

Magic can quickly feel like “cheating” to the DM who has carefully designed a forensics investigation based on science and reality. Don’t punish your magic users because they want to cast “Raise Dead” or “Speak with the Dead” on your murder victim. Just find a way around it. The body could be badly mangled, and the victim may not have seen his murderer, but the spirit could certainly provide an interesting clue, such as “I remember a green cloak, heavy, like wool, scraping my arm as he twisted it behind me” or “she was so strong, especially for being so small and wiry. Not a Halfling small, but still very short.” Let the information help them narrow down some suspects, but don’t give away everything with magic.

Using skill checks should be done often throughout the game, but shouldn’t substitute good roleplaying. Encourage your players to use their best skills to solve the crime, but reward excellent roleplaying by giving a +1 or +2 to the roll when it seems appropriate.

Powder Analysis

Setup Info: This is great for powdery substances that look similar, but have different chemical properties, such as baking soda and flour or sugar and salt. We all know from our second grade volcano project what happens when you add a little vinegar to baking soda; you don’t get nearly as interesting an effect with flour. Sugar and salt taste different, but to prevent sample consumption so that the evidence is present at trial if necessary, shape comparison with a magnifying glass is much more useful. Salt crystals are arranged like a d6, while sugar looks like a hexagonal prism (two hexagons held together with walls matching up to their sides, like the one in this picture).

DM: The Earl of Greyvel has been robbed! As he sat in court today, receiving the local townspeople and deciding on civil matters, his ruby scepter, in its stand next to the throne, came up missing. His advisor, your good friend Raolofo, has asked that you assist Captain Rossel in the investigation.

Drogan, the Fighter: Who came to see him today?

DM: Raolofo peruses the sign in sheet. “Gredo the Tanner, Falok the Butcher, Henrik the Baker, Caiern the barkeep, and Saeryn the Dancer.

Gorvik the Rogue: My brother Henrik is a suspect?! He would never do anything like this! I mean, me, I could understand…uh…that was off the table.

DM: (smiling evilly) No it wasn’t. Raolofo glances at you suspiciously, but you see no other reaction from him…for now.

Faelana, the Wizard: I rolled a 23 on Perception to find anything unusual at the crime scene.

DM: You do see a small amount of white crystalline substance next to the stand. (Pulls out a piece of paper with a sample of the sugar to be used in the analysis).

Faelana, the Wizard: Is it sugar? Bakers use sugar, and Caiern brews his own stock, so he uses sugar too.

DM: (shrugs) How can you find out?

Shaenril: I pick some up and taste it. (Reaches forward to grab sugar.)

DM: (Holds her arm so she can’t eat it.) Captain Rossel stops you. “Woman, are you mad?! You have no idea what that is! It could be poison!”

Shaenril: Oh, I didn’t think of that! My eyes widen, and I quickly shake off the substance. (Does the same with the substance that she has in her hand.)

Faelana: Then how are we supposed to find out what it is?

DM: Can you give me some Knowledge Nature checks?

Faelana: I’ve got the highest. 21.

DM: Salt crystals look like cubes, while sugar crystals have a hexagonal surface.

Drogan: We’ll need something to examine them more closely. I ask all present, “Does anyone have a magnifying glass?”

DM: Roalofo snaps his fingers, and a nearby servant fetches one from his study shortly. He hands it to you, saying, “Master Dwarf, perhaps this will do the trick?” (At the same time, the DM gives Drogan’s player a magnifying glass.)

Drogan: I nod to him, accepting it. (Examines the substance.) I think it’s sugar. (Passes it to the others to confirm).

Gorvik: (sighing) Yeah, definitely.

Shaenril: Sorry, Gorvik, but this doesn’t look good.

Ink Analysis

Setup Info: Different inks have different chemical compositions, even if they are the same color. This is great in seeing if a document is forged or if a pen found on a suspect was used to write a victim’s supposed suicide note. Although I’m using it in my scenario to throw off my PCs, it can just as easily be the clincher in a case. You’ll need to do some prep work before your players sit down at the table, though. You need two or more pens (different brands, but same color ink), several pieces of paper, and two or more cups filled with 1/3 water. Write out your incriminating document with the pen designated the “suspect pen”, and use the other pen as one that is found throughout the course of the investigation. If you are forging a signature on a document that was written with a different pen, then write out the document with another pen and sign it with the suspect pen.

Gorvik: It’s probably not the tanner, the butcher, or the dancer, but we still prove it’s not my brother!

DM: Just then a servant rushes in. “Masters, this has just arrived.” He hands you a note that reads, “If you want the scepter, leave 10,000 gold at the statue of Avandra in the center of town by midnight .”

Shaenril: Hey, we can lift fingerprints from this!

DM: Raolofo stares at you, bewildered, “Fingerprints? What is this nonsense?” This world has not discovered the science of fingerprint analysis.

Shaenril: Oh…uh, never mind. Maybe we could…find out who wrote it? Oh, handwriting analysis…or ink chromatography.

DM: That sounds more like it. Handwriting analysis may take too long to explain, but similar techniques to ink chromatography analysis are familiar and used with herbs and such in this area.

Gorvik: So how do we do that? Go around gathering up everyone’s ink?

Drogan: No, I don’t think we have grounds for that…but we could get it by other ways. Let’s get bills of sale from the shop owners…we can order a keg of ale for the earl’s party next week…how do we get the dancer’s ink?

Gorvik: Oh, let me do that…hmmm. Okay, DM, will you allow this? I got her autograph after last night’s show when I went to the after party.

DM: Good idea! Let me get that set up for you guys. (Steps away to write out bills of sale and an autograph on separate pieces of paper for each, using the same suspect pen for the dancer’s and the barkeep’s.) Give me a Knowledge History check.

Faelana: That’s me again! 27!

DM: Okay, you know that there are two basic inks sold in this town, especially since you buy so much for your spells. They are both black, and one is made from crushed insect eyes while another is made from berry juice.  Knowing what you do of alchemy, you also know that they would have very different chemical compositions. These differences will be obvious if you wet the paper and see the various bands of color that are produced as the paper absorbs the water. (She sets up several cups with small amounts of water in the bottom, and has the players cut samples from each sheet of paper and insert them in the cups.) It’s going to take a few minutes to process this, so you can do some more investigating.

Gorvin: Well, I want to go have a talk with my brother. Maybe he saw something unusual today.

Faelana: I’ll go too. (The rest of the party nods as well.)

DM: Okay, so you head over to his shop. He welcomes you, “My little brother, come in, come in…and you’ve brought your friends, too! How about some tea and cakes?”

Gorvin: Sorry, brother, I can’t today. I’m here on official business from the Earl himself.

DM: “The Earl? Why, I just saw him earlier today about the flour tax…what’s happened?”

Drogan: “Sorry, we can’t discuss that right now. Hopefully once it’s all settled, we can take you up on that tea and tell you all about it. But you may be able to help us with it.

DM: Anything for Gorvin and his friends! How can I help?

Gorvin: Henrik, we need to know if anyone is mad at you right now?

DM: Mad? At me? Hmmm…not that I know of…Sofrina, the lass that got married yesterday, seemed a little miffed that I couldn’t find chartreuse icing for her cake. Can you imagine? It would have looked like a pile of sewer muck!

Gorvin: (Shaking his head). No, it wouldn’t be her. What about the tanner, Gredo, or maybe Falok?

DM: No, no. I’ve never had any problems with them.

Shaenril: What about Caeirn, or Saeryn?

DM: “The pretty dancer and the barkeep? No…but they have come in recently. Just yesterday Caeirn came in for his sugar order, you know, for the brew. And…Saeryen was in yesterday too. Huh, imagine that…” He rifles through his sales receipts. “She bought sugar too.”

Gorvin: What would a dancer need with sugar? Maybe she set Henrik up?

DM: “Set me up?! What is this you’re talking about, little brother?”

Gorvin: Uh…that was supposed to be off the table too. Um, nothing, Henrik, we’re taking care of it! I motion for everyone to leave quickly and head for the door.

DM: Gorvin, wait! What have you gotten me into now?

Gorvin: I keep heading for the castle.

DM: You pass by the Captain and several guards and servants, as well as Raolofo. They tell you they’re heading to the garrison to continue in the investigation. The ink chromatography results are in too. (She motions to the papers.)

Drogan: Okay, the tanner’s ink doesn’t match up to the note.

Gorvin: Neither does Henrik’s, thank the gods!

Faelana: The barkeep’s autograph is a match! But Falok’s is not.

Shaenril: Hold on, we have two matches! The dancer’s!

Height/Foot Length Ratios

Setup Info: One of the easiest pieces of evidence your players can analyze is foot-to-height ratio. Check out this article for the science behind the calculate, but it boils down to this: the length of a human’s foot is roughly 15% of the same human’s height. This is a very rough estimate, so if you use this, try to use it with two suspects who have at least a 6 inch difference in height. The formula to find out the height is Foot Length/.15 (That’s point-one-five.)

DM: So you’ve narrowed it down to two suspects: Caiern, the local barkeep, and Saeryn, the dancer. One of the guards found a shoe print behind the throne, but the local guard captain refuses to take both into custody. You need to give him some solid evidence leaning towards one suspect only first.

Faelana: 25 on Knowledge Nature. What do I know about human anatomy that could assist me in narrowing it down with just a footprint and nothing to compare it to?”

DM: Good roll! You know that even if you don’t have the foot, you can narrow suspects down using a foot-to-height ratio. The foot length is roughly 15% of a human’s total height, and both of these suspects are human.

Drogan, the Fighter: Well, we can’t drag them in and measure their heights, but we can at least get close. I go back to the bar and order a pint of ale, but I remain standing. When Caiern serves it to me, I covertly compare my height to his. Is he taller or shorter, and by about how many inches?

DM: (checks her character profile on Drogan against her notes) He’s about an inch, maybe two taller than you.

Drogan: I’m 5’11”, so that makes him at most 6’2”.

Gorvik, the Rogue: I stop by the dance hall. Is there a show going on right now?

DM: Yes, all the girls are on stage.

Gorvik: Okay, I know that the average height for a woman is 5’4”. Assuming that the same is true for this group of women, where does Saeryn rank in comparison to the rest of the girls.

DM: They’re moving around quite a bit, so it’s a little hard to compare them in motion. Give me a Perception check.

Gorvik: 15. I think I struggled a little to get a good comparison.

DM: Could be. You think that she’s roughly in the middle range, not tall, not short.

Gorvik: Okay, I’m going to play it safe and estimate anywhere between 5’2” and 5’6”, still much shorter than our other suspect. I rejoin the group at the garrison.

Drogan: Me too.

Shaenril: (doing some quick calculations on paper) The footprint was 10 inches long. 10 inches is 15% of about 66 ½ inches, or 5’6½”. That’s definitely closer to Saeryn’s height!

Faelana: Let’s drag her in for questioning!

DM: Captain Rossel looks over your evidence, calls for a local doctor to confirm the foot-to-height ratio, and agrees. Saeryn is arrested and brought into his office in manacles. Outside the office, he asks if you would like to question her.

Gorvik: Most definitely!  After she tried to pin everything on my brother…I’m breaking her down!

The Closer – Grilling the Suspect

This is where the roleplaying takes center stage. Yeah, sure, you can use some Intimidate, Bluff, and Diplomacy checks to grease the wheels, but once your PCs present your suspect with mounds of irrefutable evidence and the story that links it all together, they’ll crack under the pressure!

DM: Before you sits the beautiful Saeryn. She crosses her legs, revealing her shapely calves and quite a bit of her thigh in the skimpy dance outfit. Her legs glow with health and strength, as well as beauty.

Gorvik: (whistles) It’s hard to stay mad at that, even for Henrik.

Faelana: Down boy. Her legs are glowing with beauty? Hmm…I want to ask her what her secret is to such beautiful skin.

DM: “My dear, it’s quite simple. I use a sugar scrub mixed with a little honey. Makes the skin smooth and silky. Is this why you brought me down here? For my secret recipe?”

Drogan: Not exactly, sweetie. I put the results of the ink chromatography on the table, along with the footprint measurements and the sugar. I say to her, “I’ve got a recipe of my own…for robbery.

DM: Her eyes widen slightly. “What is the meaning of this?”

Shaenril: Simple. Your footprint…your sugar…your ink. Where’s the scepter?

DM: “I…um…I really don’t know what you’re talking about….I mean, I can explain…” Just then Raolofo bursts in the room. “Explain this, you wretched thief!” and he places the scepter in front of her. The beautiful dancer glowers at him. “Fine, I did it! If the Earl would have just sponsored my trip to the capital for the audition at the Grand Theatre, I wouldn’t have needed to! I took the scepter, but then I realized I’d never be able to sell it around here without getting caught, so I ransomed it!” The guards yank her to her feet by her manacled, manicured hands and haul her to the dungeon as she screams back, “I am an artist! You can’t do this!”

Govrik: Hey, Raolofo, surely there’s a reward for this, right?

DM: Make a Diplomacy check.

Govrik: 17! That should count for something!

DM: With your -2 on dealing with Raolofo after your outburst in front of him, though, it won’t count for nearly as much. He tosses a platinum piece to you, saying, “You friends may share this, along with the Earl’s gratitude.”

Govrik: Outburst? What outbur…oh, yeah. The whole, “I should be a suspect before Henrik” thing, huh?

8 thoughts on “CSI D&D: Creating a Forensics-Based Adventure”

  1. I think the real solution would be a hybrid between GUMSHOE and 4E… keep all the 4E stuff but maybe create some (albiet smaller) investigation skills for them to spend their points on. Use the GUMSHOE stuff when running about, but then use 4E for combat stuff.

    If you check out some actual play podcasts of GUMSHOE (Esoterrorists, MCB, Fear Itself maybe?) I think you’ll see how much better the investigation flows… definitely isn’t as jerky/jarring as multiple rolls in skill challenge I’ve found.

  2. Nice right-up. Have you checked out the Gumshoe system (particularly Mutant City Blues as it includes people with powers beyond the normal person)? It solves one problem your examples do not address, what to do if a group misses a “clue roll” such as the ink knowledge roll or height perception roll.

    In your examples the DM has to make a lot of on the fly judgment calls as to what could apply in a medieval fantasy setting (ink knowledge) and what does not (fingerprints). One thing I think would be cool, and hard to do, is to see a complete write-up of what exactly a forensics system would look like in a medieval fantasy setting. Include such things as ink analysis and then make mention that fingerprints are an optional addition (honestly the only reason not to include the concept of fingerprinting is that lack of knowledge that fingerprints are unique-once past that hurdle there is no reason not to include them in a medieval setting).

    Either way, nice article.

  3. Excellent article. My experience as a DM and a player is that gamers feel a much greater thrill from a victory achieved through brains over brawn. In the article CSI: D&D we created a few of our own examples that let D&D characters use their skills CSI-style to solve puzzles and mysteries.

Leave a Comment