Drones Add a New Dimension to Crime Scene Investigations

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Anyone who’s watched the U.S. TV show “CSI” has probably seen officers carefully measuring the distance between every object in a room, and between every speck of evidence, in order to precisely reproduce the crime scene. Police must ensure they have all the information they need before releasing a crime scene, because there’s no going back to it. But now, in some areas, drones are simplifying the process, taking 15 minutes to do what takes hours by hand.

In Mesa County, Colorado, the sheriff’s department takes a unique approach. A drone shoots 90 photos in a grid, with a programmable amount of overlap in the images, in order to have enough information from enough angles to re-create the scene in 3-D. This conglomeration of photos is called Orthographic Mosaic Imaging, or orthomosaics, said Ben Miller, Mesa County’s unmanned aircraft program director at the Sheriff’s Office.

Drones lowers the cost of making orthomosaics and digital elevations models, such as this one.

Wikimedia Commons

Drones lowers the cost of making orthomosaics and digital elevations models, such as this one.

While taking photos manually to aid in crime scene reconstruction is not a new concept, drones can do many things helicopters can’t, and at a fraction of the cost, Miller said.

“One, you can’t get that close to the ground because you’ll destroy the crime scene with a helicopter. And two, you can’t take 90 photos with a big aircraft—it’s just not practical,” he said.

The orthomosaic process is unique to Mesa County. However, a few other law enforcement agencies are using drones to photograph crime scenes or to assist investigations, including the Grand Forks Sheriff’s Department in North Dakota.

Alan Frazier, Grand Forks deputy sheriff and member of the Unmanned Aircraft Systems Unit in the region, said the ability to use drones could make aerial photography much more accessible for less wealthy districts.

“It has brought the potential of obtaining aerial photos and video of crime and accident scenes to thousands of agencies rather than the relatively few (less than 200 nationwide) that can afford to have traditional manned air support units,” Frazier wrote in an email.

For Miller, photographing a crime scene with an unmanned aircraft system, or UAS, costs only $25 an hour. From a ground control station, he or another person trained in operating the unmanned aerial vehicle (UAV) will box in a certain area and tell the drone how much of an overlap to have per photo. The drone will then calculate the grid and fly autonomously. Flying at 50 feet with a 20-megapixel camera, the drone captures photos so sharp they can be enlarged to nearly life scale.

Once the photos are taken, a second piece of software assembles them into a map. This can be used to create a 3-D replica of a crime scene and to simulate possible events leading up to the crime. A replica of the crime scene can even be printed on a 3-D printer.

“It’s the detail we’re collecting that’s significant,” Miller said. “Because of the accuracy of these models, there’s all sorts of things you can do that’s very defendable in court.”

The orthomosaics are as admissible in court as any other method of crime scene reconstruction, he said, and are treated the same as photos taken from manned aircraft.

So far, these orthomosaic models have figured in the outcome of one court case and are involved in several ongoing ones. Miller hopes to set a positive precedent with UAV uses in law enforcement. However, most of the incidents where a re-created crime scene is needed in court are homicides, and those cases tend to move very slowly, he said.

In Grand Forks, the sheriff’s department partners with the University of North Dakota and local police. A small team utilizes four UAVs to respond to crises and necessary situations within 16 counties, covering 19,000 square miles, Frazier said.

“Use of UAS provides numerous law enforcement agencies and fire departments with an aerial perspective on incidents that they would not be able to achieve without the use of the UAS,” Frazier said. Drones can be operated at about 1 percent of the cost of manned aircraft, he added.

Frazier’s unit also uses drones for a better crime scene assessment, but in covering such a large area, the process differs from Mesa County’s. The department takes some photos and video with a drone but doesn’t assemble them into a 3-D replica.

As highly cost-efficient as UAVs are, Miller said, getting approval from the Federal Aviation Administration prevents more organizations from using drones. “The tech piece is easy. It’s getting permission to fly the UAV that’s probably the biggest hang-up,” he said.

The FAA needs to make rules to specifically govern unmanned aircraft, Miller said. He compared the FAA’s attempts to govern drones by the rules for manned aircraft to police officers ticketing a scooter for not having turn signals.

“Law enforcement would say, ‘We’re not going to take a rule made for cars and apply them to these little scooters.’ They weren’t written for that,” Miller said.

Frazier, who has worked with the FAA since 2010 to get the necessary permits, described the experience as “dismal” at the beginning, but showing signs of improvement.

“The FAA’s process has gotten smoother now due to dedicated folks in the FAA’s UAS Integration Office, feedback from users such as us, and congressional mandates directing the FAA to address UAS issues proactively,” he said.

If approval continues to become easier and UAV use in public safety becomes a greater priority, Miller sees its use expanding as time goes on—in cold cases, for example.

“You’re catching this crime scene in three dimensions, and in the long term it becomes a fantastic tool for cold cases,” Miller said. “Now we’ve captured that crime scene forever.”

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