Chapter 7 - Crime Scene Sketching and Mapping

Question 1

What is the primary purpose of the crime scene sketch?

Answer 1

It serves as a graphic document to show the layout, orientation, and interrelationships of the scene and the evidence.

Question 2

What are the five essential elements of the crime scene sketch?

Answer 2

· heading
· diagram area
· Legend
· title block
· scale and Direction notations

Question 3

What are two variations in creating a sketch that will effectively allow the crime scene technician to document evidence on vertical objects?

Answer 3

· cross projection or exploded sketch
· elevation sketch
· three dimensional sketch

Question 4

In rectangular coordinates, how are fixing measurements made to surrounding walls?

Answer 4

The evidence is measured at right angles from the evidence to the surrounding walls and services.

Question 5

Give an example and describe fixing a regularly shaped object with triangulation.

Answer 5

?

Question 6

In what circumstances is Baseline mapping most effective?

Answer 6

Baseline is best suited for exterior seen without evident landmarks, although it can be used inside.

Question 7

What two additional steps are required when using polar coordinates to map a scene in which elevation data are required?

Answer 7

·First, determine the difference between the datum point elevation and the sighting instrument. This distance is subtracted from the elevation reading to establish the actual elevation difference between the datum point and the evidence.
·Second, properly place the sighting device in the scene, ensuring that the sighting device is at a higher elevation than any evidence items. Failure to accomplish this last task will make it impossible to gather elevation data.

Question 8

In what situation are rectangular coordinates on a grid particularly effective?

Answer 8

Often employed in gravesite excavation or smaller scene area.

Question 9

In what situation would triangulation on a baseline be effective?

Answer 9

Situations involving exterior crime scenes where the field of evidence is not too widely scattered, but where there are no adequate landmarks.

Question 10

Why is it unnecessary to orient a total Station to true north?

Answer 10

Due to the accuracy of the total station the instrument cannot be aligned using a magnetic compass to the same level of accuracy that the total station can measure an angle. Surveying techniques suggest simply assigning a convenient North.

Question 11

What are the seven most common mapping methods used?

Answer 11

· rectangular coordinates
· triangulation
· Baseline coordinates
· polar coordinates
· triangulation or rectangular coordinates on a grid
· triangulation on a Baseline
· Total Station systems