Friday, June 23, 2017


Police, Crime Scene, Blue Light  As you know, I find the math in forensics quite interesting.  It is a way of finding information from the evidence to find the perpetrator.

On all those shows, they find the guilty person within one hour, well 45 minutes give or take a couple minutes.

In reality it can take up to a year or longer.  There was a murder in the village I live in.  A young lady was stabbed multiple times and left behind the clinic.  The police came out, interviewed everyone, gathered data, found evidence, and took forever but almost a year later, they arrested a young man for the crime. I shared one way I'd used math to prove a person not guilty of reckless driving.

Lets look at some other ways math is used in forensics to help solve crimes.

1.  One can tell an animal hair from a human hair by calculating the ratio of the diameter of medulla to the diameter of the whole hair.  If it is .5 or higher, it is animal hair.  If it is lower than .5, it is human hair.

2. Estimating the size of an individual grain of pollen using the magnification of a microscope.  The idea is to estimate how many grains of pollen will fit across and divide the size of the field of view by that and voila, you have the individual size.

3. Blood splatter uses trigonometric calculations using the height and distance to find the angle of impact.  height is opposite while distance to the splatter is adjacent.

4. Using angles, they can tell if the pelvic bones are from a male or female.  If the angle beneath the ischia bones is less than 90 degrees (forms an acute angle), it is male.  If it is greater than 90 degrees ( forms an obtuse angle), its a female. 

5. Time of death, looking at the drop in the body temperature.  For the first 12 hours, the body cools by 1.4 degrees F each hour.  After 12 hours, heat loss is calculated at .7 degrees F each hour.

6. Time of death based on insect development.  They can use the development of certain insects to approximate a time of death because insects require a certain temperature to hatch and progress from one stage to another.

If the math is packaged in something as exciting as helping to solve a crime, students are more willing to do the calculations because it is a fun and applicable situation.  I'll give some sites for creating a unit next week. 

Let me know what you think.