After spray painting his drone black, and taping over its lights, south Londoner Daniel Kelly probably thought he had a good chance of getting away with flying his now-stealthy drone into a prison yard.
So in the early hours of 25 April last year, he flew the cheap, Chinese-made quadcopter, with what police believe was a package of contraband – tobacco and possibly legal highs – attached to a hook beneath it, over the wall of Swaleside jail on the Isle of Sheppey, in Kent.
Unfortunately, he overestimated his chances: he ended up jailed for 14 months, becoming the first person in Britain to be locked up under legislation that punishes such behaviour.
But Kelly isn’t alone. He’s just one amongst many people worldwide who have discovered the potential that low-cost consumer drones have for illegal activities.
And now, investigators are launching new forensic intelligence forces of detectives to get to the bottom of drone-related crimes.
Whether it is flying illicit goods into forbidden places, spying on people, interrupting the work of the emergency services or worrying wild animals or aircraft, the threat they present is growing. Just a couple weeks ago, for instance, a drone forced five flights at London's Gatwick Airport to be diverted.
How can a criminal pilot be identified when, say, only a drone is found at a crime scene?
Identifying the pilots of remotely-controlled drones is not always easy. Drones are cheap, easy to fly, and widely available to consumers nowadays. Plus, governments are struggling to legislate fast enough to keep pace with burgeoning criminal possibilities.
That’s why more police forces are turning to drone forensics teams: it might sound like the TV programme CSI, but it’s a growing trend of more detectives whose jobs it is to track down flyers of rogue drones.
The rise of drone detectives
Just a few months ago, it was announced that the UK Prison Service and police are pooling resources to stop drone pilots from flying drugs and other contraband into British prisons, with reports suggesting that £3m could be spent on the new task force.
There’s a reason drone activity has piqued the interest of law enforcement. Drones deliver much more than drugs to jailbirds: they've been used to fly in mobile phones, hacksaw blades, knives, Sim cards, USB drives and DVD players. Not to mention they can fly over walls and barriers, complicating the operations of institutions ranging from government buildings to airports.
This makes the identification of the drone pilot crucial for law enforcement.
While Kelly's case was rare in that the pilot, the drone and the smartphone/controller combination used to operate it were all captured together. And the drone contained valid flight data that had not been erased or otherwise tampered with.
But how can a criminal pilot be identified when, say, only a drone is found at a crime scene? Or when only fragments from wreckage are found? Or when only a controller or phone is found, or when police have a likely pilot suspect but no drone?
This is where the drone detectives come in.
Tying the digital and physical facets of drone flight to a human pilot is not easy. This has led to a perception that, with drones controlled wirelessly from a distance, often unseen, it's an easy crime to get away with. Drones are cheap, after all, and can be abandoned if the flyer fears arrest.
But just as investigators only began to understand the enormous forensic resource that mobile phones represent around the turn of the century, the tougher challenges of drone forensics are now quietly beginning to be met, too.
It isn’t in the bulky device itself. It’s the fact that it’s part of a complex digital ecosystem.
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.
Different drones use different operating systems, so analysts need to be well-versed in each
How does the drone in question store flight data? How long does it store the latitude and longitude coordinates of where it was launched from? What data from the pilot's phone-based control app ends up stored in the drone too? Plus, different drones use different operating systems, so analysts need to be well-versed in each.
Sometimes the makers unwittingly help forensics teams: one drone model injects the user’s flight control app login and password – unencrypted or "in the clear" in tech jargon – on the drone. This means officers can simply log into a copy of the app and examine a user's flight video and records in cases where a crashed or dumped drone is found at a crime scene and there is no trace of the pilot.
But sometimes entire drones are found intact, too.
"We have already been involved in the forensic analysis of drones recovered in prisons, or found crashed by police forces and the Ministry of Defence," says Michael May, managing director of FlyThru Limited of Huddersfield, a commercial drone operator in the UK. "They need to find out why they were there and we can comment forensically on whatever we can find on them, whether it is on the flight log data in the drone itself, or the DNA and fingerprints on it."
A drone's rotors are reasonably sharp edged and retain traces of skin cells, he says, so they can sometimes retrieve DNA. And there are parts like the SD cards – for storing video – and batteries where users can leave fingerprints as they insert them.
It all sounds done and dusted, but some expert drone users are pretty clued up about hiding data.
So Graeme Horsman, a computer scientist and digital investigator at the University of Sunderland, took apart one cheap drone and found that there are a number of tricks a user could play to obscure where the drone has flown. He found it was possible to mask a drone's flightlog by turning off certain phone settings. He could also force the drone to store a fake location for the pilot's launch point.
A drone's rotors are reasonably sharp edged and retain traces of skin cells, so they can sometimes retrieve DNA
In other words, it’s easy for a drone pilot up to no good to cover their tracks.
Even by wrapping aluminium cooking foil around the GPS antenna, Horsman created a Faraday cage – or radio wave absorber – that prevented the drone logging its flight.
But it’s easy for that heavily protected digital data to vanish in thin air, even if the drone find its way into the hands of the authorities.
Turning a found drone off, or simply plugging in a USB cable, can cause data to be overwritten - and moving it can similarly overwrite GPS data. It all means it's vital to understand each popular drone before mishandling it or attempting forensics, Horsman says. "There are a lot of variables, so every drone investigation will be different."
Kovar says drones are already being seized for analysis: "Law enforcement seized a protester's drone at the North Dakota pipeline protests. I do not know who is doing the analysis of that drone. The drone that landed on the White House lawn was certainly analysed. And I know that people on the intelligence side are analysing drones captured from Isis on the battlefield."
What’s most foreboding, however? Experts agree: we haven’t seen the worst criminals and terrorists can do with drones. That’s why being able to identify the pilot is becoming more pressing.
"The worrying thing is that some of our drone platforms can carry 15kg (32lb) payloads. That's a hell of a lot. Terrorists could switch from using truck bombs to ones they trigger from above," May says. He warns that some could even fly international missions as drone range increases. It's even possible a bioweapon – like anthrax – could be dispersed by a drone.
"This is an emerging technology and we cannot predict the number of dodgy ways drones are going to be used in future,” says Horsman. “I think we are going to be constantly surprised at what people do with them - it's only limited by the imagination of the criminal."
Spray-painted drones, with taped over lights, look like being the very least of our problems.