Software replaces a Florida police department’s time-consuming process for classifying shoe prints found at crime scenes.
Most crimes have one thing in common — the perpetrator walked or ran near the crime scene. And those shoe prints left behind can be vital in helping police officers identify who was there while also providing evidence to a jury. But finding the type of shoe that left the print can be a time-consuming, manual process — and the hours immediately after a crime are precious.
“After 72 hours, your opportunity window of actually solving the crime diminishes greatly,” said Larry Stringham, forensic supervisor for the Cape Coral, Fla., Police Department.
Until late January, Cape Coral officers spent hours, and in some cases days, trying to identify and match a shoe print by searching through Google images and catalogs — a process that has been expedited by implementing shoe recognition software. Lt. Anthony Sizemore recalled a case he worked on six years ago in which a man stepped onto a counter while robbing a bank and left a shoe print. Forensic technicians lifted the print — a process that attaches the print to a film. The shoe’s profile was found in the bank’s surveillance video, but to identify the shoe, Sizemore spent two and a half days looking at pictures.
Although shoe print lifting isn’t the only method officers rely on to match a shoe to a print, the other techniques are also time-consuming. Stringham said in addition to taking photos, casts are made of shoe print impressions and sent to the Florida Department of Law Enforcement. It can take up to three months for the state to have an expert examine the print and its possible match, and then return a report. But the shoe print recognition software is changing this.
“With this type of technology, we would have been able to take that particular shoe print [from six years ago] and the information we had at the time, and find a match for it in about 20 minutes,” Sizemore said.
Cape Coral Police Department is one of the first in the country to use SICAR 6 software by Foster + Freeman, which has a database of more than 24,000 shoes, Stringham said. The department first implemented the company’s computerized fingerprint system, then discovered the new shoe technology. “We found out they had a shoe print classification type software, which would allow us to give information to detectives immediately on what type of shoe it is,” Stringham said. “After you get the shoe impression, you can get the side shots of it and look at the different color schemes. So it’s just more information that we can [give] to the detectives on who their suspect is.”
Forensic technicians work with shoe prints when an impression is left behind — if the person stepped in mud or snow and leaves an imprint, or if there’s a raised print, like the bank robbery case, when someone steps on a flat surface and leaves shoe residue on it.
Technicians still take photographs and make a cast when appropriate, but now the images are loaded into the software to help narrow down what type of shoe made the mark. If police have the suspect’s shoe, they use a scanner to take a digital image of its sole. This method lets officers input a shoe print from a crime scene and compare the suspect’s shoe against the uploaded print.
In addition to showing shoe images, the software provides information on the manufacturer, the date of market release, an image or print of the sole, and a set of pattern feature codes that facilitate search and match operations.
Although the software gives the shoe a classification, like Nike Air, the state’s experts from the Florida Department of Law Enforcement must still verify if the suspect’s shoe actually left the print, Stringham said.
The software, which cost about $10,000, has already proved its worth in Cape Coral. About a week after deployment, Sizemore said a man broke into a commercial building, which he accessed through an alley. “He broke a window and climbed in through the back,” he said. “When he landed on the first couple of steps, he left muddy shoe prints on a terrazzo floor.”
Forensic technicians took digital photos of the prints and loaded them into the system as an unknown person. Within days of the burglary, police officers pulled over a driver with a suspended license when he abandoned the car, ran and jumped into a canal. The police eventually caught him, but while he was swimming, his shoes had come off and sunk.
The detectives investigating the burglary identified the same man as a suspect, but when they went to question him he was already in jail. The department’s dive team retrieved the shoes from the bottom of the canal. “We scanned them,” Sizemore said, “and they came up as a match as those that we had already imported from that earlier burglary.”
Had this happened before the software was in use, the retrieved shoes would have been sent with the photos and impressions to the Florida Department of Law Enforcement. “It would have been about a four-week turnaround,” Sizemore said, “and we did it in about an hour.”
If the department hadn’t quickly verified that the shoes matched the burglary scene, the man would have been released on bond for the driving offense and could have relocated. And in some cases, Sizemore said, the extra time allows a suspect to destroy evidence.
Although the software has helped Cape Coral police, like all technology, it’s not perfect. Stringham said photographs can be deceiving, so technicians must follow procedures to ensure that the software works optimally.
“If you leave the impression in the dirt, mud or snow, then you get the reversed [photograph] of that — the furrows are now the ridges and the ridges are now the furrows,” he said. “So you have to be very careful to make sure you invert the image and do all the proper procedures to make sure you put it in so that it will actually do a good search.”
There are other limitations, too. The software couldn’t identify a running shoe that a reporter asked the department to classify. Stringham said he researched the shoe and found that it was about 12 years old, but the database only goes back 10 years. The vendor provides quarterly updates to keep the database updated with the newest shoes.
Although the software is new, Stringham predicts it will become popular with law enforcement agencies. “Once other agencies start seeing the utilization of this through our and other agencies, this system will probably be just like the fingerprint system — I think it’s going to grow exponentially fast.”