Category Archives: The Armchair Detective
Armchair Detective: Bloodstain Sequencing
As I’ve written before, the examination of bloodstain patterns can be crucial in reconstructing the events of a crime. Blood is fluid and thus can be influenced by the actions of bleeding subjects and others in contact with wet blood. As a general rule; the more blood present the more we may be able to tell about the actions and events comprising the commission of a crime. Make no mistake though, this is very difficult stuff to analyze. I’ve spent over a decade studying bloodstain patterns with some of the best practitioners in the world. It may seem simple and straightforward but there is a lot more to consider than just the bloodstain patterns. For now, let’s just look at a simple exercise of recognition and sequencing. You don’t need any background information for the photo in order to conduct this exercise. Assume all of the blood seen is from the same individual. I’m not going to tell you the cause or manner of death. Focus on the blood and rely on your common sense.
Before you begin, take a few moments to refresh your recollection of some basic bloodstain properties by reading about passive flow, skeletonization, and other basic properties of blood.
Take a look at the photo and try to figure out two main actions taking place. Keep it simple. The more detail you try to discern the more inaccuracy you’ll probably create (unless of course you’re a professional). In the end, see if you can sequence any of the events you’ve described. If you could ask only one question what would it be?
UPDATE:
Well, I was hoping for a few more responses but perhaps this one was too difficult? For those that are interested here are a few main observations. Notice the large pool of blood (the darker red horizontal area). That indicates that the victim was laying near that position for some period of time (as opposed to walking through or running by). Then, do you see how that blood is separated into two halves (larger one on the left, smaller on the right) with a lighter ares cutting through at about the center of the photo? That particular pattern is repeated directly above it. Now look to the right against the wall. You should see two bloody right hand impressions (palm and finger tips on the right side of the blood pool). What these two types of marks indicate is that the victim crawled through the blood pool on his hands and knees. Can you envision that? These patterns taken together indicate (generally) that the victim was injured (to produce external bleeding) then collapsed on the cement where he bled to produce a large pool for an undetermined amount of time. Then after that he became mobile again and crawled through the blood which had already congealed (this is why the two pools remained separated). Now there is a ton more going on but it won’t make much sense without understanding all of the case details which I won’t go into but, I hope you can see that the analysis of bloodstains can reveal important clues at the crime scene. If I were to ask one additional question it would be about the condition of the victim’s clothing, specifically the knees (and hands) which should both be bloodstained if they produced these marks.
Armchair CSI: Unusual Road Mark
Imagine you are a park ranger on Trail Ridge Road and you come across this strange mark on a roadway. You look around but see nothing unusual. What would you make of the mark and does it give you an idea of what to do next?
I guess I need to make these a little tougher because you all did really well. The mark was produced by a spinning vehicle tire on it’s side (during a roll over). It is what I would loosely call “impression” evidence. I like this photograph for a couple of reasons. First it forces the young CSI to consider associations. In this case if a student were stuck I would simply begin by asking what kinds of “circular” objects could be found on roadways? This is a very simple and common problem solving tactic in crime scene investigation and reconstruction. We have to do this type of analysis in bloodstain pattern analysis all the time. Consider a “pointy” shaped object leaving a bloody outline on a bed sheet following a stabbing. What kinds of “pointy” things might you find associated with a stabbing? If you said “a knife” you’d be right. Of course there could be a lot of things that could fit that broad description but you get the point. It won’t be a baseball bat right?
So, continuing with this tire photo. The next thing this image forces a student to do is to think of crime scene events three dimensionally. Most of the time cars drive upright (on all four wheels) but not always. When don’t they? Accidents. So if this is an accident on a high mountain road what might you be looking for? Perhaps a vehicle off the side of the road right? In the mountains that may be several hundred feet down a mountain side. Now in reality this mark was found in a city roll over accident, but the investigative process is the same. The last thing I like to use photos like this for is to reinforce that we need more of the picture before we draw any hard conclusions. The same is true in writing. Sometimes as authors we over-simplify our scenes and the evidence. The evidence and the scene makes sense to us because we wrote the scene. But the reader may be coming at it from an entirely different direction. Suddenly your “ah-ha” evidence can be interpreted another way. So, when possible, run some of your evidence discovery scenes past another writer or friend and see if they come to the same conclusion as your characters did.
Next month I promise to give you a more challenging photo that deals with bloodstain pattern analysis and sequencing events. So if you want to get a leg up on your fellow readers take a look at some of my past postings on bloodstain analysis. Thanks to all of you for taking the time to share your thoughts and opinions for this series!
The Armchair Detective: Unusual Marks
This is the second installment of The Armchair Detective series. Remember, there are no “wrong” answers. This exercise is designed to get your creative juices flowing and hopefully pull you out of any creative ditch you may be stuck in. Here is the fictional scenario;
There have been at least three rapes over the Winter months wherein the suspect forcibly enters the victim’s ground floor apartment. The male suspect enters by prying open sliding windows after removing the screen. Once inside he makes his way to the bedroom and covers her mouth with whatever he can find (victim’s clothing). He then rolls them over and presses a “weapon” into their back. The women couldn’t identify the weapon but said it was cold, heavy, and solid like steel. The women were not injured by that object and showed no “marks” on their skin. The victim’s report that the man wore all black including a face mask and leather gloves. The suspect has worn a condom and the rape kits have come back with negative or inconclusive results. One woman remembered a strong cologne but didn’t know what brand it was. Two of the women originally didn’t report the rape but revealed the crime to friends days later. Detectives are sure there are other rapes not being reported but they don’t really have much to go on.
The police set up a tip line and one unknown woman called in to say a man she dated acted strangely including wanting to “role play” a rape. The man did live within a five mile radius of the victim’s homes so detectives decided to pay him a visit. They found the man working on his car in the garage and he invited them in to talk. The man vehemently denied having anything to do with the rapes. While the detectives talked to him they spotted some strange marks on the garage floor and took a quick photograph before being asked to leave. The marks had general class features but no identifiable marks. Here are some questions. Do you have a theory as to what caused the marks, are they important, and can they be used to search for other similar cases? The ruler in the photograph is 13″ (32.5cm) long
Leave your comments below and I’ll chime in after a few days.
Unknown marks on garage cement floor
The Armchair Detective: Case #1 The Traffic Stop
I wanted to try something new with you folks and I’m calling it the Armchair Detective series. Basically, I’m going to post photos and pose questions in order to teach you a little about the investigative process and forensics. This is a little trick I used to use with students and interns and I think it might be fun to try it here with you too. These exercises can be very helpful in teaching individuals how to view and value evidence and as authors I thought you might reap some of the same benefits. So here is how it works. I pose a question or series of questions usually connected to some kind of imagery and then I give all of you several days to a week to respond with your observations. Most of the time you won’t have all the information you think you want or need but that is precisely the same challenge of the CSI. If nothing else, these will provide you with a handy excuse to take a break from writing and exercise another portion of your brain. Ready?
Case #1: The Traffic Stop
Imagine the images below were taken from a “traffic stop” and you are the CSI. What clues can you discern from the content of the images submitted by the officer? Can you tell me anything about the driver? In short, tell me what you see that a law enforcement officer should take notice of. Since this is a theoretical exercise don’t be too concerned about taking a leap or generating a theory. While I am looking for certain answers treat it as if there are no right or wrong answers. Have fun and comment as often as you like. I’ll give you my observations after several days. Good luck!
