A crime has been committed. The police are on the scene, looking for clues and evidence. This is a job for forensics.

That's when a highly trained group of experts arrives at the scene. For the Pennsylvania State Police department, that would be the Forensic Service Unit.Trooper John Corrigan of the Hazleton barracks and trooper Brian Silliman of the Fern Ridge barracks are members of the state police Forensic Service Unit. They visited the Western Pocono Community Library summer reading program in Brodheadsville, bringing their van filled with all the equipment they use when investigating a crime scene."We always start with a camera. This one is about $8,000," Corrigan said as he showed the children. "It can detail fingerprints and footprints."Other important tools are a video camera to record distance, infrared camera to pick up blood splatter, duct tape for retrieving fingerprints, a Honda generator so lights can be plugged in, a stepladder, materials to mold footprints and tire prints, and a metal detector.Diagrams are then made of the scene."When we go to court, we have to have accurate facts," Corrigan said.He explained how important math and science is to investigating blood splatter.Luminol is used at a crime scene that is bloody. Even if bleach is used to clean up blood, there are still traces of blood there. He said a few weeks ago, they revisited a crime scene that occurred in 1991, and blood was still found there. A black light will also help in highlighting blood.He documented an accident scene in which someone was killed. He looked for paint transfer. The autopsy of the victim showed black paint chips on the body which could help determine if it was an accident or intentional.Cellphones are also powerful tools for the police because they can help determine location."I am never bored," Corrigan said.He showed the children the items he carries as a trooper such as handcuffs; an ASP baton; his firearm, a Glock .45; and extra magazines for it. The one that interested the kids the most was his stun gun, but he told them that the pepper spray he carries hurts worse."You could taser me all day long if you don't pepper spray me. That stuff hurts," he said.He told the kids that it is legal to carry anything for defense, but if it's used, you can come under scrutiny.He showed them the cameras and his laptop inside his cruiser. The camera starts as soon as the flashing lights are turned on. Once someone is placed in the back seat, the doors are locked and you can't get out.In the trunk, a trooper carries flares, a bag with an emergency disposable blanket, caution tape, gloves, spray paint, duct tape and a spike strip used to disable a vehicle by puncturing tires."A criminal always brings something to the scene, and he takes something away from the scene," trooper Dan Peters said.It's the job of the Forensic Service Unit to determine just what those things are.