CRMJ 332 midterm
Part 1 of 1 – 91.0/ 100.0 Points
Question 1 of 1 91.0/ 100.0 Points
You have a crime scene with a female stabbed with a knife; you will assess the blood stains in the crime scene diagram provided;
1) Identify what you think the bloodstain patterns are and what there characteristics should be,
2) Detail what you feel caused the bloodstain patterns,
3) Detail what you feel occurred at the crime scene.
You will find the bloodstains in alphabetical groupings for your convenience in identification and descriptions groupings A through H (A is directed to the body area and G is directed to the S/W area of the residence).
CRMJ332BLOODSTAINMI DTERMDIAGRAM222NOV2 010.docx 94 KB
Blood Spatter Analysis
This is the midterm scenario in which we were told to describe what we think happened here. Although I did have a bit of a hard time due to lack of information, I think that I may have figured out that the victim was attacked in her kitchen and tried to get away and the offender tried to clean up the crime scene, although unsuccessfully.
It looks like the victim may have been doing dishes. There is no obvious damage to the from door, so I am thinking that the victim may know the offender. It looks like the first injury was in the lower right quadrant of the abdominal cavity with a kitchen knife. The abdominal cavity houses things such as the large intestine which has many blood vessels, the appendix, multiple lymph nodes and the femoral artery which runs right next to the cecum in the lower right quadrant of the abdomen. This is an example of ejected blood, which happens when blood leaves the human body by force. This forms an arc that can be calculated mathematically. The blood can land in it’s final trajectory based on gravity, wind currents, temperature, humidity and friction. There may have been humidity from the heat of the water from the dishes. Gravity was in definite play. Depending on the temperature of the living area, it may either speed up decomposition or slow it down. There are no obvious wind currents but there may have been depending on whether or not there was a fan, air-conditioning or heating.
It looks like the first strike was there in the living room because the victim may have heard a knock and went to answer the door but the offender made it in before she had a chance to react. Although she may have been attacked in the kitchen with blood stain D, that may be a transfer stain. A transfer stain is that of when blood is transferred or smeared from one object to another. I also noticed that she had wounds on her right hand and arm. She is right handed and was possibly trying to fend off her attacker. Those may be defensive wounds.
A closer look at the crime scene I think the victim was stabbed in the kitchen with a knife from her own set. That would explain blood A. Blood B I think is that of falling blood from the wound. It may have just dripped on the floor next to the dishes. The separation of these drops from the primary source of blood, blood A, is caused by the constant gravitational forces exceeding the cohesive forces of the surface tension. (Bevel & Gardner)
Blood C might have been caused by her movement into the other room to try to get away from the offender. The elongation of the blood drop is produced by the drop contacting and wiping or skidding against the target surface. Blood E & F are either cast off or from the force of the femoral artery if it was severed. When a free falling drop of blood traveling through the air and strikes a non horizontal surface, the resulting blood stain is more oval or elliptical and elongated relative to the angle of impact.
Blood G I think was transferred from the blood stained towel and the foot wear impressions that may or may not be blood covered. I think that blood H may just be cast off material which happens when blood is acted upon by an outside centripetal force. Of course blood H could be considered a transfer stain if there was a struggle. The scenario isn’t very forthcoming with that information.
I think that Ms. Jane Doe was in the kitchen cleaning up dishes when her attacker probably knocked at the door and came in. This might have been true especially if she knew her attacker. Blood stain A is obviously the ejected wound in which may be the source of all the blood this may also explain blood B. It might be the blood falling that caused that stain. Blood C is definitely a transfer blood stain. The victim either was dragged or she was trying to get away by crawling away. Blood stain D may be considered a transfer stain. That might have been from the victim trying to leave or the offender moving the victim across the floor. Blood E&F may either be cast off or ejected blood. Like I said it depends on whether or not the femoral artery was severed. Intestinal blood doesn’t usually cause that of a spurting motion but more of an oozing. The blood stained towel may have been used to clean up blood b causing blood C. The footwear impressions come from the soles of the offender, which are about as unique as finger prints. One can be found using this because everyone walks differently so the soles of their shoes wear out differently. Blood stain A is also considered an acute injury. The location of livor mortis on the body may also indicate post mortem movement of the victim when the location of the settled blood is not consistent with the position in which the body was found at the scene.
The spherical shape of blood in flight is important for the calculation of the angle of impact (incidence) of blood spatter when it hits a surface. That angle will be used to determine the point of origin. (The diagram does not give enough details for me to calculate this) I did try to calculate the area of convergence which I believe to be between the kitchen and the living room. Across from the bedroom. All of the lines seem to intersect there. The term point of origin has also been accepted to mean the same thing as area of origin. There is a small problem with this idea. The blood source is not a point source, to accomplish this the mechanism would have to be fixed on a three dimensional axis which is impossible unless only one blood drop was released at a time. Bodies are also dynamic, meaning skin is elastic and bones break, that is a side from a body in motion. Newton’s third law of motion states one enough force is applied to the body there will be an equal and opposite reaction to the force applied by the offender. Part of that source, then will move the blood source, and change the origin slightly This then contaminates the source in a three dimensional region. Photography might be the best solution for this to help with the point of origin that might be non contaminated.
I think that the victim was attacked in her kitchen and she tried to get away. The offender tried to clean up the crime scene, obviously unsuccessfully.
2) onlinecourses.scien ce.psu.edu
3) Bevel, Tom; Gardner, Ross M. Bloodstain Pattern Analysis With an Introduction to Crimescene Reconstruction, 3rd Ed. CRC Press 2008
4) James, Stuart H, Eckert, William G. Interpretation of Bloodstain Evidence at Crime Scenes, 2nd Edition, CRC Press 1999