Forensic Evidence

Forensic science is the study of anything that relates to a crime. The basic principle behind forensic science is the belief that a criminal always leaves something behind.8 Forensic pathology, or medical jurisprudence, is the study of medicine as it applies to the law.9 Using forensic science, criminologists discover many important facts that lead to solutions to crimes. For the purposes of this interactive mystery program, evidence that would require advanced technology will be represented on paper or in a simplified form. “Detectives” will compare evidence from the crime scene and believed to be left by the culprit with samples of like items gathered from the suspects.

Clue and Suspect Table


Clue #1 - the Handwriting on the Note

Clue #2 - the Lip Print on the Glass

Clue #3 - the Poison in the Cup

Clue #4 - the Fingerprint on the Cue Stick

Gregory Blackwell





Delia Jones





Kayla Masters





Ellen Smart





Clue #1: The Fingerprint on the Pool Cue

History. In 1891 Juan Vetuchich introduced the first fingerprint registry. This system classified prints into four types: internal loops, external loops, whorls and arches. A detective compared prints found at the scene of the crime with every set of print on file.9

Science of Fingerprinting. Each fingerprint is unique. The raised lines that make up the fingerprint are called friction ridges. When someone touches something, body fluids are left behind in the pattern of the ridges. While some fingerprints are visible, others are latent and may need chemical treatment or dust to be seen.10 There are four basic types of fingerprints: arch, loop, whorl, and combination.

Making Fingerprints. To make fingerprints for the suspects and the culprit, rub the sharpened end of a soft pencil on a piece of paper. Place a piece of tape (sticky side up) on a table. Rub the finger across the pencil lead on the paper. Place the finger with the graphite from the pencil lead on the tape. Carefully lift the finger to see the fingerprint. Tape the fingerprint onto a white piece of paper or a note card. Fingerprint several the four individuals who are role-playing the suspects. Put those fingerprints on a poster. Under each print write the name of a suspect. The actor who is playing Ellen Smart should make two fingerprints, since she is the suspect who left a fingerprint on the pool cue. Tape one of her fingerprints to a separate piece of paper and write “suspect” under it to represent the fingerprint that was found on the pool cue.” Teens will compare the suspects’ and culprit’s prints

Clue #2 – The Lip Print on the Glass Found in the Billiard Room

Science of Lip Prints. Cheiloscopy is the study of lip prints. Lip prints are unique and mostly unchanging during a person’s life.11 Women who wear lipstick may leave lip prints on a rim of a glass. The fluid on anyone’s lips may also leave prints, although these are more difficult to find.

Making Lip Prints: The easiest way for the suspects to make lip prints is to press their lips on white or light-colored paper while wearing lipstick or gloss. Although making a print on a plastic glass will look more realistic, the print will probably show up better on a flat, white surface. Make lip prints of each of the actors playing the suspects. Put those lip prints on a poster and write the names of each suspect underneath them. Since Delia Jones left the lip print on the champagne glass, that actor will make two lip print samples. One will appear with the lip prints of the rest of the suspects. The other will be taped to a separate paper under which “suspect” and “lip print found on the glass” is written. Investigators will compare the fingerprints of the four with the print on the glass. This is a red herring since Delia did leave the print but did not kill Nathan.

Clue #3 - The Handwriting Found on the Note in Nathan’s Pocket

Science of Handwriting. Handwriting is one of the ways to analyze a document through forensic science. Often incriminating handwriting is found on kidnappers’ letters, on the backs of business cards, as an imprint on the page beneath which something was actually written, etc. Each person’s handwriting is very unique. Professionals can compare handwriting samples. Even if a person attempts to disguise his or her handwriting, specialists may be able to match handwriting samples of that person with the evidence. Different methods are used to analyze cursive writing and printing.

Alphabet Comparison Handwriting Analysis. Alphabet handwriting analysis involves carefully comparing the letters and connections of letters in handwriting samples. Often suspects will be asked to write the following sentence: “The quick brown fox jumps over the lazy dog.”

This seemingly silly sentence contains every letter in the alphabet. Detectives determine which suspect’s handwriting is most like the culprit’s handwriting by comparing suspects’ handwritings samples with the culprit’s handwriting. The detectives look for similarly open or closed loops in letters such as “e”, “a”, and “o”. They would also compare letters such as “b”, “l”, and “f” which have either closed or open extensions above the line, and other letters and letters such as “p”, “f”, and “q” which have either closed or open extensions below the line. Another comparison point is in the rounded or pointed nature of letters such as “s”, “n”, and “m”. The slant of the writing is another clue.

Each suspect will write “The quick brown fox jumps over the lazy dog” and the handwriting samples will be attached to a poster. Print the name of suspect underneath the appropriate handwriting. Another staff member will pretend to be Nathan Masters and write on sheet of stationary “We have to talk – soon.” Attach the stationery to the poster with the rest of the handwriting samples. Write “handwriting on the note found in Nathan Master’s pocket” underneath the stationery This clue is another red herring. Although the note was found in Nathan’s pocket, he wrote it with the intention of delivering it to Delia. None of the suspects’ handwriting will match.

Clue #4 – The Time of Death

The time at which a victim actually died can often be an important factor in determining who had opportunity to commit a murder. Determining time of death is not an exact science, but there are a series of body changes that can give an approximation of the time of death. Unusual conditions can cause these changes to be delayed or expedited.12 Below is a summary of the appearance of a corpse at various times after death.

Summary of the Appearance of a Corpse after Death

30 minutes:

The skin has a waxy, blue-gray color. Lips and nails become pale.

Up to 3 hours:

The skin turns white when pressure is applied and the color changes when the body is moved (the body is livid.) The body is still warm to the touch. There is no rigor mortis.

4-6 hours:

The body becomes cool to touch. Early rigor mortis, the progressive stiffening of the muscles that occurs several hours after death as a result of the coagulation of the muscle protein, begins in the jaw and neck.

6-8 hours:

Skin is purplish on the underside of body, whitish on the top, and does not change when the body is moved (fixed lividity.) The blood is coagulating. More advanced rigor mortis appears in the arms and upper body. Corneas become cloudy and opaque.

By 12 hours:

Full body rigor mortis sets in. The body is totally “frozen”.

By 18-24 hours:

The body is cold and clammy to touch. The skin is greenish-red. Rigor mortis begins to resolve and the neck and jaw relax.

30 hours:

Rigor mortis is fully resolved and the body is limp.

Poisons - Symptoms and Availability13

Arsenic – Symptoms of arsenic poisoning are severe stomach upset, dizziness, vomiting, convulsions and coma. Skin may look yellow or become cold and clammy. Arsenic is one of the most common poisons and is used in manufacturing glass and wallpaper, is an ingredient of weed-killers, and used in taxidermy.

Cyanide – Symptoms of cyanide poisoning are immediate unconsciousness, convulsions, and death. The skin may become flushed pink. Blood may be cherry red. A bitter almond smell is often found on the victim’s breath or body. Death occurs within 1 to 15 minutes or longer. Cyanide is used in making insecticides and in some medical drugs and is found in many plants, including apple seeds and peach pits.

Nicotine – Symptoms of nicotine poisoning are a burning of the mouth and throat followed by nausea, difficulty in breathing, convulsions, coma, and death. Death occurs within 5 minutes to four hours. Nicotine is used as an insecticide and is commonly employed to kill rose-aphids. It can be extracted from cigarettes by soaking them in water.

Strychnine – Symptoms of strychnine poisoning are stiffness and then severe convulsions, causing the body to “jack knife.” Rigor mortis sets in almost immediately. Death occurs 15 minutes to several hours after ingestion. Strychnine occurs naturally in some plants. This colorless, odorless powder is very difficult to get.

Nathan Masters’ Body When Found

  • Masters appeared to have undergone convulsions or a struggle.
  • His body temperature felt cool but not cold.
  • Rigor mortis had spread from the neck and jaw into shoulders and arms.
  • His skin was livid (purplish) and did not change when his body was touched.
  • His corneas had begun to cloud over, turning white.
  • His skin had an almond smell.

Show a poster describing Nathan’s appearance when found, the “Summary of the Appearance of a Corpse after Death,” and the “Poisons - Symptoms and Availability.” After comparing the victim’s appearance to the chart and the information on poisons, detectives should be able to determine that the death occurred between 8:00 and 10:00. This means that Delia could not have committed the crime since she was seen until around 12:00 midnight. Also, detectives should determine that he was poisoned with cyanide that is found in many pesticides. Pesticides were readily available to Ellen, an avid gardener.

Conclusion – Ellen Smart Did IT! She is the only suspect who left a fingerprint, who could easily have gotten some cyanide, and who has no alibi for some times in between 8:00 and 10:00.

8 Gardner, Robert.

Crime Lab 101: Experimenting With Crime Detection. Walker, 1992.

9 Petersen, Sandy, and Lynn Willis.

Call of Cthulhu; Horror Roleplaying in the Worlds of H.P. Lovecraft. 5.1 ed. Chaosium Inc., 1992.

10 Wiese, Jim.

Detective Science: 40 Crime-solving, Case-breaking, Crook-catching Activities for Kids. Wiley, 1996.

11 Wiese, Jim.

Detective Science: 40 Crime-solving, Case-breaking, Crook-catching Activities for Kids. Wiley, 1996.

12 Wilson, Keith D., MD.

Cause of Death: A Writer’s Guide to Death, Murder, and Forensic Medicine. Writer’s Digest Books, 1992.

13 Stevens, Serita Deborah, with Anne Klarner.

Deadly Doses: A Writer’s Guide to Poisons. The Howdunit Series. Digest Books, 1990.

Page last modified: March 2, 2011