The glitter trail that leads straight to an arrest.

The comedian Demetri Martin often jokes that glitter is the herpes of craft supplies. The line always gets a big laugh, because anyone who’s ever encountered glitter in any form knows that once you’ve been exposed to the stuff, you’re stuck pulling tiny particles from body crevices and couch cushions forever.

The police have also noted glitter’s maddening clinginess, and figured out a way to use it for good. In a paper titled “Glitter As Forensic Evidence,” retired criminalist Bob Blackledge argues that in criminal investigations, glitter provides an ideal way to trace criminals to crime scenes.

There’s a scientific theory called Locard’s Principle. It says that every time a person makes contact with another person, place or thing, they leave a physical trace. These traces let forensic scientists find connections between suspects, victims and crime scenes.

In his paper, Blackledge sets out the seven qualifications for an ideal “contact trace,” which is a term used to refer to the physical fragments left behind when any two objects touch. The trace should be nearly invisible and easy to transfer and retain, he argues. The ideal trace should be highly individualistic, easily collected and characterized, searchable via computerized database and able to withstand the environmental factors that might cause it to break down over time. Using his own scoring qualifications, Blackledge argues that glitter is the perfect contact trace.

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The idea that cops can use glitter to catch criminals is not new — I even found a paper on the topic that was published in 1987. And as an investigative tool, glitter’s not perfect: Blackledge tells Evidence Magazine that one of glitter’s flaws is its sheer variety. He points to one specific company in New Jersey which claims to offer more than 20,000 types.

This diversity makes it difficult for forensic scientists to definitively prove how rare a particular sample might be. Forensic scientists frequently testify as part of criminal proceedings and their inability to provide statistics about the likelihood of a specific strain of glitter appearing at a specific crime scene makes it easy for prosecutors to pick apart their testimony.

Also, glitter’s usefulness depends on whether there’s already some glitter at the crime scene or on the criminal or the victim. That’s a minority of situations.

Travis Glass was convicted of murdering 13-year-old Steffini Wilkins in 2001 after investigators found glitter traces that connected him to the crime scene. | Missouri Dept. of Corrections

Even so, law enforcement has been able to successfully utilize glitter in their investigative work. In his e-book, “Forensic Analysis on the Cutting Edge: New Methods for Trace Evidence Analysis,” Blackledge cites a case that took place in Florida in 2004. A mother and daughter died after a drunk driver in a pickup truck rear-ended their car. Police discovered the driver hiding nearby, but she denied operating the vehicle. Police were able to identify her using her cosmetic glitter, some of which had transferred to the driver’s seat airbag at the time of the collision.

In a Missouri homicide case from 2001, investigators used glitter found on the 13-year-old victim’s jeans and bedspread to connect her murderer to the crime scene. In an Illinois kidnapping and assault case, police were able to match the glitter from the 12-year-old victim’s shirt to the clothes worn by the perpetrator.

So the next time you open a greeting card and glitter falls out, do not despair its ubiquitous nature. Instead, celebrate. Because that glitter may help police hunt down your murderer some day.