Forensics for Writers: Evidence and Investigation

I’m at Millennicon this weekend, and I was up a wee bit too late last night celebrating my brother-in-law’s birthday. I also hung works of art in my first art show, which was vary exciting. Oh, and had a midterm exam in Anatomy & Physiology. So… I’m a bit brain-dead.

I debated including this section (You can find part one here, and the second part here). Strictly speaking, evidence collection is very important to forensics – don’t do it right, and you risk destroying evidence, or not collecting vital pieces, or… so many mistakes can be made. But it is a tedious process, and one that is likely to be boring to readers. But on the other hand, it’s vital to building a case if done right. Also, I have a handy case summary from a class assignment, and I desperately need more coffee before returning to the con.

These are the evidence collection notes, then summary that the investigator would present to a prosecutor who would then determine if the case was worth pursuing. It’s interesting to note that something like 20% of robberies are ‘closed’ which is, resolved in some way. Only 20%, and normally DNA testing would not be allowed to the investigator for budgetary reasons on this relatively minor crime. I have to wonder as DNA tests become faster and cheaper if the robbery closure rate will improve.

12/24/2010 2243 Crime Occurred

12/24/201 2330 Arrival on scene of investigator

  1. After conversation with officer on scene, investigator began preliminary scene survey, taking overall photos of the front of the store, the entrants, the parking lot, the freshly swept sidewalk. The investigator then proceeded to the rear of the store to photograph the alley the suspect had been seen fleeing into, per the officer on scene. Before entering the store, the investigator also photographed the locations of the video surveillance cameras.
  2. During cursory search, one cigarette butt was collected from swept sidewalk after photographing it in place and with scale. The investigator is wearing gloves and will be for the duration. The butt was collected with gloved hands, placed in a small bag, sealed, labeled, and the note made to send it to lab for analysis of brand (classification) and possible DNA (individualization).
  3. As responding officer stated he had not entered the store, the investigator used oblique light to locate and photograph footwear impressions as the clerk had just cleaned floor. Used sticky lifter and powder to preserve impression for comparison to clerk’s footwear and exclusion for suspect.
  4. The investigator took a buccal swab from the clerk (Slim Pickins, DOB 4/1/69) and exclusionary fingerprints. Buccal swab should be done while gloved, and sent to the lab in the provided box or envelope for DNA testing. Before fingerprinting, a GSR test was done on the clerk’s hands, and finally footwear impression prints were made for exclusionary purposes.
  5. Obtain the clerk’s gun from him in exchange for a receipt. Recorded the serial number ABC 123, and photographed the gun and serial number. Secured in special box with zip ties. Sent to the lab to be test fired, analyzed for fingerprints, and compared to spent shell casings with tool marks.
  6. In the store, the investigator photographed the overall scene, then photographing the bag of chips, once in situ, once with scale ruler. Carefully collected the bag of chips for potential fingerprints. Secured with packing material to prevent shifting and damage to potential prints in the box.
  7. Collect, after photographs in place and with scale, the packet of cigarettes from the counter to test for prints in case the suspect touched them. Again, secure in a box to keep from sliding and damaging prints rather than placing in a plastic bag where friction could obliterate the prints.
  8. Photographed the bullet casings in place and with scale. Collected into small containers, separately, to be analyzed for tool marks or fingerprints.
  9. Collected the plastic cash tray after photographing in place and with scale. Place in large box, secured, to be analyzed for fingerprints. Find out if there are other clerks to get fingerprints from them for exclusionary purposes as well.
  10. Check the cash register for fingerprints. Lift and package for the lab to analyze.
  11. Collected all the cigarette packs the bullet had traveled through, photographing them in place, with scale, and again as each is removed. Left the bullet in the last pack and note this for the lab. Ask the lab to analyze for markings on the bullet and the packs of cigarettes can be used for determination of trajectory. Record on evidence the order of the cigarette packs so the lab can put them in proper order.
  12. When officers reported the discovery of the jacket, the investigator went to where it was found and photographed it in place, with scale, and then each item as it was discovered. Collect the jacket to be tested for DNA from cuffs and collar. Secure in paper bag with note to check for hairs.
  13. Photographed the ammunition in the pocket, by holding it open, then place scale and photograph again. Collect in vial containers, keeping it separate, for comparison with the spent rounds in the store (classification) and fingerprints (individualization).
  14. Photograph receipt and place in evidence envelope to be tested for fingerprints.
  15. Obtained the video surveillance footage for both the time of the crime and the earlier purchase time (plus an hour before) of 7:25 per the receipt found in the jacket. Investigator reviewed them to look for customer with the jacket and named items, and then for the crime itself.

Presentation of evidence and facts in the case #10-69075 with recommendation to proceed in detaining one Cody Criminal, DOB 01/01/85; SSN:123-45-6789 for questioning about the robbery at Quickie Spirits ‘n More at 2243 on 12/24/2010. A warrant to search his residence for the weapon used in that robbery should be issued.

On the night of the robbery, a man entered the Quickie Spirits ‘n More at 2243. The clerk observed him to discard cigarette butt onto the freshly swept sidewalk as he entered the store. The investigator later recovered the butt and the lab analyzed the DNA and found it to be consistent with Cody Criminal. The man stepped into the shelves and picked up a bag of chips, bringing it to the counter. He laid them down on the counter and asked for a packet of cigarettes. The clerk stated that the man’s breath smelled of beer and cigarettes. The bag of chips was recovered by the investigator later and a latent print was taken from them, after running through IAFIS the print was determined to be the right index print of Cody Criminal.

The clerk testifies at this point that the when he turned around from getting the cigarettes, the man was pointing a gun at him and demanding ‘all the cash.’ The clerk started to comply, opening the cash register. There was a brief struggle and the clerk took his gun from below the counter and fired it at the suspect (this was confirmed by GSR residue on the clerk’s hand), the man then fired back, his bullet striking the cigarette packs in the rack behind the clerk. Laboratory testing matched one casing to the clerk’s gun, but were unable to match the casing or spent bullet to a firearm in NIBIN. The suspect’s firearm is sought for comparison purposes.

Following the shooting, the man fled on foot to the rear of the store. Police officers searching later discovered an Alabama “Roll Tide” jacket one block away with unspent ammunition and a receipt in the pocket. The jacket was tested for DNA which was determined to be consistent with that of Cody Criminal. The receipt, from the Quickie Spirits ‘n More on the same date as the robbery but at 1925, was found to have a latent print which was run through IAFIS and confirmed to be from the left thumb of Cody Criminal.

Review of the video surveillance by officers showed that a man matching Cody Criminal’s previous mug shots had been in the store and purchased the items on the receipt at the time stamped on it, and that he was wearing the Alabama Roll Tide jacket at the time. Again at the time of the robbery, the video showed a man in a Roll Tide Jacket entering the store and confronting the clerk. Based on the physical evidence there is sufficient basis to proceed with an arrest and warrant to obtain the firearm used in the robbery.


  1. 20% closed is certainly believable to anyone in law enforcement. There are probably another 20-50% where they have a really good idea about who is responsible, but just don’t have enough evidence to bring charges. And of that 20% that are closed, figure the prosecutor is going to plead a bunch of those down just to avoid trial. Regardless of the old saying, Crime Does Pay.

    1. And recidivism is something like 80% I’m told. I’ve had a couple of good instructors – former and current LEOs – and plenty of friends who have been willing to talk to me as I embark on this. I’m leaning not toward law enforcement, but working in a lab, a big difference.

  2. I love police procedurals, but I’ve never tried one. Just as well, since I haven’t got the background, and would have to research extensively.

    Even then, I suspect that actual police experience would be almost a requirement to get the voice and tone right.

    1. I would suggest just sitting down and talking to a couple of cops. Or joining a local Citizens Police Academy (they have them for Fire, EMS and Dispatch as well, depending on area). Around here there are several departments that have something like Coffee With A Cop every month, or some even every week. I’m sure you could find several in your area that would be willing to sit down with you and talk about stuff.

  3. One thing you see a lot with first response is people get the view that the job is fast paced, always doing heroic acts and stuff when you could just as easily be woken up at Oh dark thirty because granny rolled out of bed and not turn a wheel otherwise. Tend to see a lot of people burn out pretty quick between that and just how screwed up our ‘You call, we haul, you lose our bill’ mentality is. The classes are doing better in the last 10 years training people just how routine 911 is, but people still have a invalid view from TV.

    I hope you don’t mind if I include web addresses for these in a handout for a panel I am running on Mystery/Thriller writing in a few months. Just dilletante stuff but I get a number of questions from people as to how I write accurate characters vs the standard tv stereotypes (As well as when to break accuracy)

    1. I am writing these to use as resources, share away! I am thinking a couple more weeks of the series, since I want to cover some more science and fiddly bits like blood spatter and toxicology.

      1. I was assuming so but since the entire lit world seems up in arms again over permission to recommend I figured I’d ask. Admittedly I’m hesitant to recommend too much from this site for fear of audience reaction but this definitely fits and it’s pretty obvious (Although I say that and we all know that that is a loaded word). And as long as they are linked together it will make a good series even if it’s still in progress in May. It’ll be interesting to get information that I can use from the people that loathe me (I’m an Evidence Mangling Technician).

        On a more general note, I wonder if there should be a tag solely for writing advice vs publishing advice vs promo advice and such with some sort of definition of each pinned to main page.

        1. Some of the writers here use tags and categories – I do – others don’t. So that won’t help, I’m afraid. I will probably publish all the links together when I put the last post up, for ease of clicking.

          As for recommending things from MGC, this is primarily a writing site, the side-tracks come and go. Either people can judge us on the efforts we go to for the community, or they can take offense at them. Nothing I can do about that. All I can do is offer useful content, as a way of paying it forward for the help I’ve been given.

          1. You mean you’re all not really a hive mind?

            Admittedly the use of MHN for firearms writing advice will probably be just as bad so whatever. Most of it will be research sites rather than raw writing anyway.

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