The Gatwick airport shut down investigation, due to invading drones on the aircraft landing flight path has cost £790,000.
Seven different police forces in total were deployed to investigate the two drone users.
Gatwick airport was shut down for 30 hours causing 1,000 flights to be cancelled affecting more than 140,000 passengers at the time.
Sussex police reported that 129 separate sightings of the drones which all had to be investigated that began on December 19th 2018.
109 of those sightings were deemed credible and witnesses included pilots, airport ground staff and police officers.
Officers across the seven forces took more than 220 witness statements and made house visits to over 1,200 people.
Police have now stated it had to be an “inside job” with the drone flyers having inside knowledge of the airport.
The police are determined to catch the culprits who remain at large.