KNOXVILLE (WATE) – Walking up to the Subway on Sutherland Avenue, from the outside it may just look like any other sandwich shop, but it’s the new device inside that aims to keep crooks away.

“It’s exciting to lead in something that’s not just on the food side of things,” said Subway Director of Operations AJ Underwood.

Above the front door sits a new style of security, called the Intruder Spray System. It’s the first of its kind in the country and the Knoxville Police Department is excited to try out.

“It’s another tool in our tool bag to help fight crime, especially violent crime, which is what a robbery is,” said KPD Deputy Chief Gary Holliday.

What sets the system apart? It holds synthetic DNA, which sprays robbers as they walk out the door.

“If law enforcement apprehends him up to seven weeks following the incident, they can shine a light on him and they can see that he was marked,” said CSI Protect Senior Vice President Johan Larsen.

Each store gets its own unique code. Investigators then trace the marked man or woman back to the crime committed.

It’s technology proven to work. In the past decade it’s been used in 30 countries with great success.

Subway hopes the new signs now hanging in the store window make would-be robbers think twice before committing a crime.

“For the KPD it’s great, they can catch people who do this, but I think for us it’s the factor of deterring people from even doing it at all,” said Underwood.

KPD and CSI Protect plan to partner with more stores throughout the Knoxville area to install this style of device.