Forensic Science provides a unique way to tap into the natural curiosity that is the basis of science. The framework for the scientific method is present at any crime scene, making observations, asking questions, formulating hypotheses, and finally testing the ideas are all part of the who, where, and what of a crime scene. Forensic science via deductive reasoning and experimentation will provide the vehicles to deliver science to a new generation of students. There are many simple and safe experiments that can be done in a home setting that will not only introduce forensic science to the student, but also teach deductive reasoning and critical thinking skills.

……Springing into action Lydia carefully observed the scene and made a quick sketch of the location of the items remaining on the ledge. “Don't worry Mom, I will figure out who took your ring!”….

Your student can help Lydia and her mom solve the mystery of the Missing Ring by performing the following experiments. As you'll see, forensic science labs can make science learning a lot of fun!

The Case of the Missing Ring: While the basic elements of the experiments below can be performed on their own, it is more fun and provides a more relevant learning experience if you involve friends and create a CSI drama for this exercise. There are two related experiments which will help solve this mystery: Finger Print Analysis and Napkin Chromatography.

Materials Required:
o Three or more friends and/or family members to play the roles of suspects
o A different brand of non-permanent black felt marking pen for each participant
o A small, clean dry glass for each participant plus one extra
o A full or half sheet of black construction paper
o Talcum powder, may substitute loose face powder, corn starch, or similar
o Two white napkins for each participant
o Pencils for each participant o Magnifying glass
o Ruler o Scissors
o Clear tape o Water

Set-Up Procedures:

1. Invite three or more people to participate in creating the evidence for this mystery and solving it. Give each participant:
a. A different brand of non-permanent, black felt marking pen
b. Two white paper napkins
c. A short, clean dry drinking glass

2. Instruct the participants that you will leave the room and need each of them to:
a. Tightly grasp and release their drinking glass as they set it down on a counter or table
b. Use their marking pen to draw a 2.5 cm (about 1 inch) long line 1 cm (about 4/10th of an inch) from the bottom left edge of each of their napkins as shown in the illustration at right.
c. Use their marking pen to also draw a unique symbol such as a square, circle, triangle, etc. on the upper right corner of each napkin. However, the mark should NOT be their name, initials, or anything that personally identifies them
d. Place their two marked napkins in a line behind their drinking glass so each participant's glass and marked napkins are grouped together.

3. Ask the participants to leave the room. When they are gone, select one set of drinking glass and marked napkins to be the Suspect in this case.

4. From one of the Suspect's napkins, tear off only the upper left corner containing the unique symbol. Place this piece of napkin in a drawer or out of sight until the experiment is complete.

5. Carefully pick up the Suspect's glass by gently gripping only the very top and/or bottom to avoid smudging the existing prints and arrange the glass and the torn Suspect's napkins on a window ledge as described in the above crime scene. While not absolutely necessary, this step provides authenticity to the experiment.

6. Remove the remaining participants' glasses and store them for later use

7. Throw one of each of the remaining sets of napkins in the trash. All that should remain on the counter or table at this point are one each of all the participants' marked napkins.

8. Call the participants back into the room so they can observe and participate in the actual experiment.

Question: By not observing the participants mark their napkins and thus not knowing which set of drinking glass and napkins belong to each participant, you will be a “blind” or non-biased examiner when you evaluate the evidence. Why is it important to have blind examiners evaluate evidence in crime scenes and other types of scientific investigations?

EXPERIMENT 1: Finger Print Analysis:

Background: Genetics plays a role in not only how you look but also in the details of your finger prints. Every person has a set of finger prints that are unique to them. This is why investigators can use fingerprints to identify if a suspect was present at a crime scene.

A latent finger print is one that is hidden and cannot be seen with the naked eye. One way to make latent fingerprints visible and more evident is by “dusting.”

Finger Print Analysis Procedures:

1. Carefully pick up the Suspect's glass by gently gripping only very top so you don't smudge the existing prints.

2. Gently shake a light film of talcum powder or similar over the glass to expose the finger prints. Blow off the excess powder and carefully set the Suspect's glass aside for comparison with the finger print records you will create.

3. Instruct the participants that you will leave the room and need each of them to :
a. Gently place a piece of sticky clear tape over their thumbprint and a second piece of tape over index finger print. .
b. Carefully peel off their two print tapes and stick them in a row onto the black construction paper.
c. Draw the same unique symbol used on their napkins next to their row of finger prints on the construction paper
d. Call you back into the room when all finger prints have been taken and secretly identified.

4. Use a magnifying glass to carefully observe the sets of finger prints collected and compare them to those “dusted” on the Suspect's glass.

Question: If you have a match then it is possible that the suspect was at the window ledge where the ring was left. Do you think this would be enough to accuse someone? Always consider all evidence before you make an accusation.

“Mom we can rule out Dad! His prints are definitely not on the glass but Aunt Susan's are. Let's check out the napkin, Aunt Susan was jotting directions down last night, but I also saw Billy doodling on napkins as well”.


EXPERIMENT 2: Napkin Chromatography:

Background: Chromatography is a very useful tool in forensic science that allows for the analysis and identification of complex mixtures by separating them into the chemicals from which they are made. Each different marker brand manufacturer has a unique formula that makes up the black ink in their marker. In this simple experiment you will use chromatography to separate the color pigments of each ink brand and to identify which marker was used to mark the napkin left on the window edge. Chromatography is often used in forensic science with many different water and alcohol soluble substances.

Napkin Chromatography Procedures:

1. Set out a separate drink glass for each participant's napkin on the table and one for the Suspect's napkin on the window ledge. Place approximately 2cm of water in each separate drink glass.

2. Starting with the participants' napkins and finishing with the napkin from the ledge, perform the following for each napkin strip:
a. Cut a 2.5 cm (approximately one inch) wide strip from the bottom left to the top left and of the napkin. This strip should have a black mark about 1 cm from its bottom.
b. Roll the top end of the napkin strip around a pencil. Hold the pencil and napkin strip outside of the glass and roll or unroll the napkin strip so that the bottom of the strip will just barely touch the water. You may need to add or remove water in the glass so the strip's bottom will just barely touch the water. Tape the properly adjusted napkin strip to the pencil.
c. Set the pencil with the strip of napkin on top of the glass so that only the tip of the napkin strip is in the water as shown in the image below. Make sure that the ink mark is NOT in the water!
d. Place the remaining portion of the napkin containing the identifying mark in front of its related glass.

3. Observe how the water is absorbed by the napkin strips and separates the marker ink colors as it moves up the strip.

4. Once the chromatography process has completed and the ink colors have separated out, and working with one participant's napkin strip at a time, remove the strip and compare it to the Suspect strip. When you find the strip that has the same separation pattern as the Suspect napkin strip from the crime scene, you have one more piece of evidence to accuse the suspect with.

5. Check your results and confirm the identity of your Suspect by:
a. Verifying if the symbol associated with the chromatography matched napkin strip is the same as the symbol on the piece of napkin torn off of the Suspect's napkin at the beginning of this exercise.
b. Verifying that the symbol associated with the matched chromatography strips also matches the symbol associated with the matched finger prints.

“Mom, I think you had better check with Aunt Susan, she is possibly the one who may have your ring”.

Question: What do you think Lydia found when she compared the napkin strips from the chromatography experiment?

These experiments are examples of how science can be reframed into a creative investigative discipline. Students are taught to observe, to systematically collect evidence, to experiment and to come to rational conclusions. Although these are very simple examples, there are many other experiments that can be done at home for more advanced students. More detailed experiments might include plaster casting foot prints or tire treads, microscopic analysis of glass, fibers or hair, even blood typing; these can all be done in an at home setting.

Kate Lormand, M.S. has been an adjunct biology professor for 20 years and teaches online as well as face-to-face courses. Her Masters Degree is in Plant Genetics and Agriculture. Kate also works with Hands-On- Labs, Inc. (www.LabPaq.com) as a biology researcher to develop effective laboratory experiments for inclusion in LabPaqs. LabPaqs are academically aligned collections of science equipment and supplies that allow students to perform traditional science experimentation at home. Various LabPaqs in biology, chemistry, geology, and physics are used by thousands of online and alternative high school and college students each year. Kate has three sons, and her family spends a great deal of time gardening and attending swim meets.

Designing science experiments to coordinate with a crime scene mystery is a wonderful way to actively engage students in science study and introduce them to the genuine joy and thrill of discovery a study of science provides. Those parents interested in more advanced forensic science experiments for their students will be happy to learn that Hands-On Labs, Inc.  www.LabPaq.com is currently developing a forensic science LabPaq that should be available in 2009.