Blood SpatterBy:

Jen JendraszekJackie Heider

Blood Spatter

By:Jen JendraszekJackie Heider

By:Jen JendraszekJackie Heider

Directionality and Distance of blood droplets.

Depending on the distance and direction that blood is dropped from a surface, the shape and size of the droplet will be affected.

The shorter distance the drop is from the surface, the smaller and smoother the droplet will be.

Distance . . . FROM 10 CM

above the surface…› Notice how the

droplets are smooth and have a 1cm diameter.

› AVERAGE: 1.1cm.

Distance . . . FROM 30 cm above

the surface…› Due to the increase

in distance from the surface the blood spatter has grown larger and shows signs of scalloping.

› AVERAGE: 1.43 cm.

NOTE!!! SCALLOPING:

› The distortion around the edges of the droplets.

Distance . . . FROM 50 cm

above the surface…› The splatter is

noticeably larger with a wider spread of scalloping and secondary spatter.

› Average: 1.58 cm.

Point of Convergence!

The point of convergence is the central point of the spatter and indicates the location of the removed object.

With the point of convergence determined you are then able to tell the origin of the blood spatter.

Determining the Point of Convergence…

By drawing lines through the long axis of the various eliptical blood drops you are able to see where the object had been or the spatter had originated.

Blood Flinging!!!!! Aka the Cast Off.

When blood is hits a surface at an angle the spatter elongates, creating an oval (or eliptical) shape. At the end of the oval shape a tail may appear following the flow of the “cast off” (the tail always points in the direction of travel).

The Cast Off.

Determining the angle of trajectory for blood droplets…

By measuring the width and length of a blood droplet you are able to calculate the angle of trajectory.› Length: .5cm› Width: 1.0cm› 0.5/1.0 = 0.5cm› With that information we

are then able to determine the angle of trajectory by comparing the measurement in the Appendix A: Sine Table; giving us an angle of 30 degrees.

Angle of impact determination…

In order to find the angle of impact of a blood drop divide the width by the length.

You then take that measurement and locate it in the Appendix A: Sin Table.

Appendix A: Sine Table

What we did . . .

We alternated the angles of the paper from first 30 degrease and then to 45 degrease and finally to 60 degrease.

For each alteration we dropped blood onto a plane sheet and allowed it to dry.

Once the blood spatter dried we then took measurements, comparing the results to the Appendix A: Sin Table.

From this observation we were able to determine the angle of impact.

From 30 degrease…

Because our droplets were too large we were unable to determine the proper angle of trajectory; however the proper measurement should have amounted to 60 degrease.

Note… Though we angled the paper at 60

degrees, the proper angle of trajectory is 30 degrees because the angle of the surface added to the angle of trajectory must amount to 90 degrease

(30 + 60 = 90 degrease.)› 30 degrease was the angle of the paper.› 60 degrease was the measurement the

calculations should have amounted to in the Appendix A: Sin Table.

› We know this because 30 + 60 = 90, and 90 degrease is the angle a flat surface.

From 45 degrees…

Our measurements amounted to:› Width: 1.2› Length: 1.7› 1.2/1.7= 0.7› 0.7 reads out to be

45 degrees.

From 60 degrees…

Our measurements amounted to be:› Width:1› Length:2› ½= 0.5› 0.5 reads out to

be 30 degrees.

Conclusion…

Blood spatter (bloodstains) can be used to help piece together events that resulted in bleeding; the information blood spatter provides can aid an investigator in his search to determine if a crime was committed or not (and if so if the blood can be considered as evidence in the crime at hand).