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

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About forensics4fiction

Hi there. Thank you for visiting my BLOG for crime writers. I hope you will find it interesting. I would love to hear your questions and thoughts regarding forensics and criminal investigations. I hope that the information here will help answer your questions or ignite your imagination. I am a retired senior criminalist with 15 years of forensic experience. I have served as the president of the Association for Crime Scene Reconstruction, Rocky Mountain Association of Bloodstain Pattern Analysts, and the Rocky Mountain Division of the International Association for Identification. I am triple board certified in forensic related fields and one of only 40 board-certified bloodstain pattern analysts and 80 board-certified footwear examiners worldwide In addition to writing over 60 scientific papers, I have worked as the editor of the Journal of the Association for Crime Scene Reconstruction, been interviewed by and consulted for television, books, magazines, and newspaper articles including documentaries on the Discovery Channel and National Geographic.

Posted on January 11, 2012, in The Armchair Detective and tagged , , , , , , , , , , , . Bookmark the permalink. 15 Comments.

  1. Perhaps the marks are from the weapon he’s using when raping the victims. One woman claimed it was cold, heavy, like steel.

  2. Looking at the pattern; it looks like the clips on the ends of battery-jumper cables. Although it resembles that pattern, and it is winter time, I can’t see that being used to push into someones back.
    I would speculate the weapon is what the perp used to pry open the sliding window. A small pry bar, or tire iron, would serve double duty in this case.

  3. The shape reminds me of a car jack I once saw.

  4. I was trying to think of what he could be using for a weapon? It looks like he drug it across the floor.

  5. I was reminded of a car jack too — maybe the rapist uses it to get to a hard-to-reach window. He might use the lifting pin from the jack as a weapon. His “strong cologne” could be WD-40 or some kind of mechanic’s hand cleaner.

    But what the marks most remind me of are my footprints when I’m wearing ice grips stretched over my boots — postal carriers wear them, and they’re great for hiking in winter. If the rapist wore them, investigators could possibly find footprints in snow or dirt outside the windows or on the floors of his victims. If the marks on the garage floor are muddy, perhaps investigators could compare soil samples from the scenes and the garage floor marks.

  6. I think they were two imprints from the same item. If you look closely, they have irregularity and asymmetry to them which are consistent between the two marks. So you could overlay the two marks and consider the areas present in either to be part of the original. I think they’re too irregular to be either the snow coil shoe or carjack items, as they would be more straight.

  7. Great! Another one of these! Thanks Tom!

    This has nothing to do with the metal object poked in the backs of the victims, btw.

    I am with Sierra Bufe (and made this part of my analysis before opening up the comments btw), I think this is the same item, in an open and a closed position perhaps. My first thoughts are that these are something used to secure something else, likely a victim and especially the limb(s) of a victim if it is a known fact that he is wanting to role play a rape.

    What sort of limb? Measuring the width of the device by comparing pixels of the ruler and of the device, I get (6.8cm). Length is 11.2cm. A wrist would easily slip out of this but I think it would hold an ankle. And looking at the general diamond cross section, that roughly matches the dimensions of an ankle. Now, something designed to hold an ankle (or rather, lower shin) could be designed this crudely because as long as the foot doesn’t make it over the device, the victim’s ankle is secure. This will work with a wide variety of foot and ankle sizes for that reason.

    I’m really not sure how the device works exactly because it appears to me as though the bits on the closing side lengthen somehow (or perhaps it’s just the lengths of the edges touching the surface are changed (e.g. to weight difference).

    I suspect this might be heavy and made of metal (e.g. steel) given the fact that marks are left on the concrete. It may be attached to something else (e.g. some sort of wooden structure perhaps).

    I think that this is very suspicious and that his house should be searched to find the object that made these impressions.

    1. Do you have a theory as to what caused the marks?
    Yes. They are some sort of clamp used to hold the lower shin/ankle of the victim secure for use in rape, probably after an abduction.

    2. Are they important?
    Yes, very. They are going to be used to secure the victim, to make it easier for the rapist to rape at his leisure, and also to be able to come and go without worry of the victim escaping. This also suggests that this guy is about to start abducting his victims, if he hasn’t already. That is because using the victim’s home as a place to keep his victims is a dumb idea and will increase his likelihood of getting caught. So he will either bring his victims to his house, or to some other remote location (e.g. his workplace, a forest, or an abandoned house, something like that.) And he will very likely murder his victims. He is going to make the jump from rape (lower penalty, easier to get caught) to rape and murder (higher penalty, higher and more prolonged enjoyment for him, harder to get caught because less evidence can potentially be left and there is no victim to identify him).

    3. Can they be used to search for other similar cases?
    Yes. I would look in any vehicles this guy owns, along with any work vehicles he might use. I would look elsewhere everywhere in his house, perhaps an attic, shed, crawlspace. He should be made to procure the item. If he can’t, there might be a victim somewhere languishing in this very item who is now or is about to become known as a missing person. Perhaps even somewhere else in his house or on his property.

    I would not expect to find marks where victims are, in general. It might be worth putting something in the local news for rape victims or people with a boyfriend/hookup to come forward who have had their ankles secured by some sort of clamp of this nature.

    I would put him under 24 hour covert surveillance or at least GPS monitor every vehicle he might use. This will give a good guide to locations to search.

    Other comments:
    I think think that it is highly likely that this is the same individual performing the rapes. Everything about the rapes suggests organized planning and intelligence – that he is doing everything in his power not to get caught. He may ultimately have the goal of murder, but perhaps he is starting out slowly to gain experience with something (rape) that will not jail him for life or get him executed.

    To compare that with this suspect, he is intelligent (or he would not be smart enough to work on stuff in the garage). The rape “role play” also would go hand-in-hand with the sort of extremely organized, methodical type of criminal we are dealing with here. He would want to practice and iron out the bugs before proceeding to a real live victim.

    The strong cologne suggests to me either that he takes a lot of pride in his appearance, or that he doesn’t want to be identified by body odor if he has a peculiar body odor, and uses cologne to mask this. One of the things I would put in the search warrant (house, workplace and vehicles etc.) would be for cologne, which could be used to identify him. This cologne could be used to identify him either through the nose of the victim (i.e. her memory) or the nose of sniffer dog. The cologne smell would surely be on his clothes, and if he used a vehicle to get there rather than walking, it would be on the front of the driver’s seat of the vehicle. (I say all this because he might be so anal as to buy the cologne on the night and discard it then and there at the store. The rest of his MO suggests this sort of meticulousness. It could be useful to do some dumpster diving near each outlet where cologne could be bought in the area.) Hopefully the woman has not washed the clothes she was attacked in.

    In summary, I think that there is a good likelihood that in this scenario you are dealing with a rapist (quite possibly a sexual sadist) who is about to take a big jump from rape to murder. Everything that belongs to this guy needs to be thoroughly searched. This guy needs to be caught ASAP.

  8. One other thing – looking at the picture again, I now think that these may be the prints from two identical ankle restraints (rather than the one device in two different modes). One is open and one is closed. They are about a foot apart and in the same direction corresponding to the ankles/lower shins of a standing woman.

    Perhaps these two restraints are connected as part of some sort of block that might be able to be secured to something else or perhaps just heavy enough that it is more than a woman can lift.

  9. They look like tongs to me– the heavy-duty kind.

  10. It could have been something being dragged in that pattern. It would have had two points of contact, something on the feet which could be rubbed off onto the concrete (like white rubber bumpers), and there were four major movements to create those shapes on the floor.

    Perhaps a ladder or a step stool coming off of a tall vehicle?

  11. Congratulations Jena you are exactly right. The marks are from a pair of Yaktrax brand ice cleats. Here’s a [picture. The clues were the white colored residue and the fact that there were two. It could be that it was a single item placed in two positions but given the uniformity of the discoloration my mind goes to “pair”. Since this is in the winter you have to ask yourself what could leave a white residue on the ground in winter. If you live in an area that uses a lot of magnesium chloride (or similar products) as de-icing agents then you’ve undoubtedly seen lots of “white” colored shoe impressions in building entry ways and sidewalks.

    There is no way to know if the man is connected to any of the crimes (especially from only one single tip) and while his sexual preferences might seem strange, even criminal, they are not rare. Still, correctly identifying the marks could provide a lead to follow. If any unsolved burgalries had these types of footwear impressions at the scene, and if the burglary victim also admitted to being a rape victim, then ….maybe. Thanks to everyone for making a lively discussion and congratulations again Jena.

  12. Well done, Jena!

    One thing that is somewhat strange is that this guy asked the police to leave after they took a picture of these innocuous marks – they are just innocent tracks from cleats, right? If I was innocent of a crime and in the same (embarrassing) situation I think I would feel compelled to give them more of an open book. And explain what the marks are from, and offer to show them.

    Look forward to the next one of these exercises.

  13. Thank you! :)

  14. I missed this! Sorry I did. I thought it look like scissors jack, never even seen ice cleats before! Congrats Jena

  15. Don’t feel bad, it’s not a competition. I really just use these to get the creative side of your brain engaged.


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