Presentation on theme: "Something to Think About 'Wherever he steps, whatever he touches, whatever he leaves, even unconsciously, will serve as a silent witness against him. Not."— Presentation transcript:
Something to Think About 'Wherever he steps, whatever he touches, whatever he leaves, even unconsciously, will serve as a silent witness against him. Not only his fingerprints or his footprints, but his hair, the fibers from his clothes, the glass he breaks, the tool mark he leaves, the paint he scratches, the blood or semen he deposits or collects. All of these and more, bear mute witness against him. This is evidence that does not forget. It is not confused by the excitement of the moment. It is not absent because human witnesses are. It is factual evidence. Physical evidence cannot be wrong, it cannot perjure itself, it cannot be wholly absent. Only human failure to find it, study and understand it, can diminish its value. ' -Professor Edmond Locard
Your Thoughts How do you think Locards’ statement has affected the way we investigate crime today? Team up with one classmate. How do your responses compare? Do you agree with your classmates answer?
Cheiloscopy Cheiloscopy: is the study of lip print patterns. Research has shown that lip prints can be considered unique based on several factors. Line patterns on the lips Shape of the lips Point by point differences between individuals
How can Cheiloscopy be Used? Everyone has lips. Lip prints are unique to an individual. Lip prints left behind at a crime scene can be compared to those of the suspects.
Difficulties There are some issues that make lip prints less reliable than fingerprints. People can change the shape of their lips. Lips are not commonly touched to as many different kinds of surfaces as fingers.
Other Uses for Lip Prints Lip Prints made with lipstick can be analyzed to identify the lipstick used. Lipstick is a blend of different chemicals and pigments. Each lipstick brand and color contain different mixtures of these chemicals.
How Can We Compare Lipstick? Paper Chromatography: is a method used to separate the pigments in a substance. Lipstick found at a crime scene can be compared to known samples using paper chromatography.
Paper Chromatography A sample of the lipstick is applied to a paper medium. The end of the paper is dipped into a liquid solvent (ex. Water, alcohol, acetone) As the solvent travels up the paper, pigments are carried with it. A pattern will be formed based on the solubility and mobility of the pigments in the lipstick.
Tomorrow In tomorrows class we will examine lipstick found at a crime scene using paper chromatography.