at the Crime Scene
Now that you have classified fingerprints,
how can they be identified when found at a crime scene?
Fingerprints must be removed and transported
to the crime lab. They are then compared to the database of fingerprints
on file. One way that detectives locate fingerprints is by dusting
for them. Fingerprints are coated with powder, then lifted and taken
for identification at the lab.
Try your hand at being a detective by dusting
for fingerprints. You will need the materials listed on the right.
1. When fingers are oily
or sticky you get better fingerprints. So press an oily or sticky
finger on the side of a drinking glass.
2. Coat the fingerprints with a dusting of cocoa powder.
3. Brush gently with either
a camelhair or fiberglass brush. The fingerprints remain.
Place the sticky side of the tape on the dusted fingerprint. Lift on the tape and place on light colored construction paper.
- Talcum powder should be used on dark surfaces.
- The dusting method is used to lift prints from hard surfaces. Lifting prints from smooth surfaces requires chemicals.