One of the most unjustifiable fingerprint cases I was ever involved in was a latent print from a small piece of plastic found in a dormitory hallway at the University of Arizona.
I checked out an evidence submission from Property & Evidence for processing and found numerous torn shards of plastic from a green two-liter soda water bottle. The offense listed was criminal mischief. I superglued the pieces of plastic and found one good latent fingerprint. I photographed the latent and compared it to the fingerprints of a suspect named in the evidence submission. The latent print matched one of the subject’s fingers. I wrote my report and forgot about the case.
A month or two later, I received a call from the County Attorney. He wanted a pretrial conference with me. The defense attorney did, also.
When I showed up at the prosecutor’s office, he explained that the shard of plastic was from a “dry ice bomb.” It had been placed outside a dorm room door late at night in a prank, apparently to startle or awaken the resident of that room and others along the hallway.
My kids had experimented with dry ice bombs in the back yard. They would take a two-liter plastic bottle with some water in it, then drop in a few pieces of dry ice and screw the cap on tight and come running into the house to watch. The evaporating dry ice would eventually create pressure exceeding the strength of the plastic bottle and it would explode with a noise I would equate to a shotgun blast. The resultant shards of plastic were too light to have much momentum and fell to the ground without going far. There was very little water spray, mostly just a puddle.
I commented to the prosecutor that I could not say that the print on the plastic shard was left by the person who set off the dry ice bomb. It could have just as easily have been made on the plastic by somebody who had drunk from the bottle or had simply handled it prior to its use as a noisemaker. The prosecutor brushed off my objection.
A moment later the defense attorney arrived and began to question me about the identification. I showed him photographs and charted enlargements, following which he turned to the prosecutor and announced his client would accept the plea deal.
I wanted to scream “STOP! WAIT!” But it was not my place to do so. The plea had been offered before I arrived and accepted before I could respond. The defense attorney had never bothered to ask whether the print could have been left innocently on the bottle by someone other than the person who had made the device.
To make matters worse, the defense attorney had just pled his client guilty to a Class 2 misdemeanor, not a mere Class 1. That meant a more serious permanent record for a harmless college prank of a loud bang. After the defense attorney had left, I asked the prosecutor how in the world a loud bang from a dry ice bomb constituted a Class 2 misdemeanor. He said that the janitor could have cut his finger while picking up the torn shards of plastic. I told him I thought that was about the most “chickensh**” case I’d ever heard of. And to this day, I still think the defense attorney did his client a terrible disservice by taking the plea offer without questioning the relationship of the fingerprint to the alleged offense.