All these issues are adding up to a need for more investigative tools, says James Mackler, an attorney specialising in drone litigation at Mackler Law Firm in Nashville, Tennessee.

"Drone forensics are becoming increasingly important as more drones take to the air. Civilian commercial drones are now being used by terrorist organisations and the fact that they are being weaponised makes forensics all the more critical." He knows the risks more than most: he’s a former US Army helicopter pilot who flew missions alongside military drones in Iraq.

The need for drone-specific law enforcement extends to civilian safety, too. Crowds at football matches, concerts and protest marches have been regularly buzzed and endangered, too. At Seattle's 2016 Pride parade, for instance, a woman suffered concussion after a drone smashed into a building and dropped on her.

And, of course, the drone's potential for invasion of privacy is profound, leading some people to shoot them down with all the risks public firearms use entails. Indeed, that has led to Mackler attempting to clarify drone airspace law after one of his clients had his drone shot down by a neighbour – and a federal judge let the shooter get away with it. It’s not clear in US law, Mackler says, where a householder’s airspace ends and FAA-governed civilian airspace begins.

Unlocking the system

So how will authorities catch any drone-flying criminals?

The secret isn’t in the bulky device itself, says David Kovar, a digital investigator and cybersecurity consultant based near Boston, Massachusetts. It’s the fact that it’s part of a complex digital ecosystem.

This “ecosystem” includes peripheral devices like smartphones, controllers, and sensors that collect data like GPS position and crash analysis data from accelerometers, compass heading, and video images. And metadata in the video will reveal where shots were taken, including altitude.

So investigators do actually have a lot to go on forensically, Kovar says, even if they don't have all the physical components. After all, a drone may crash and fracture into pieces, or only a remote may be recovered at the scene.

"But of them all, the biggest source of information is the mobile device, the phone or tablet," Kovar says. And investigators are well versed in pulling those apart.

But here’s the challenge: it is a diverse marketplace. Each drone has its own digital quirks.