The Lips Don't Lie
Criminals may need to start thinking twice before puckering up at a crime scene. Two TSU graduates recently did a study that may prove to be beneficial to those in the forensic science field. After doing a study on identical twins' lips, Alexis Davidson, BS '05, and Hilary Wilson, BS '05, found that though their lips are shaped and sized similarly, the crease arrangements of each individual's lips and their prints are distinctly different.
In their paper, Davidson and Wilson noted: Lip prints bring added evidence to a crime scene that can be valuable, especially when lacking other evidence, like fingerprints. Lip prints can be a factor in many different kinds of crimes, such as: tape when a person has been bound or gagged, prints on a glass that a person drank from, prints on a cigarette butt, and prints on a glass/window if they were pressed up against it. All of these are potential places where lip prints may be found and used in the investigation of a crime.
In the study, five sets of twins, ranging in age from 14 to 29 were used. Four different types of data were collected from DNA swabs, tape pulls, glass prints, and dental casting of the lips. The DNA swabs were used to determine that the twins had indistinguishable DNA, hence monozygotic twins. The women also demonstrated the persistency of the creases of the lips by obtaining another set of casts of the lips about a month after the initial standards had been obtained.
"Studying monozygotic twins helps demonstrate uniqueness," said John Vanderkolk of the Indiana State Police laboratory. "If repetition of patterns in nature were to be found, monozygotic twins should be the place to find repetition. There are far too many factors to occur for patterns in nature to be replicated. Hence, all patterns in nature are expected to be unique."
Cheiloscopy, the study of lips, is a fairly new science. The use of lip prints in criminal cases is limited because the credibility of lip prints has not been firmly established in the court system.
"The reason cheiloscopy has yet to be to admissible is that it hasn't been tested in the courts and really the literature on the topic is pretty limited," noted Criminal Justice Chair Dr. Craig Laker. "The topic needs to be tested more in the scientific community, using the scientific method, before it is an accepted use of identification. In addition, you would have to qualify as an expert witness, meaning you have done extensive studies on the topic, and very few scientists have."
This just demonstrates how TSU students are thrust into the forefront of their field. Whether it's lip prints or DNA swabs, these two graduates learned that lips don't lie.