It may be the fastest animal on land, but one cheetah was stopped in his tracks when he came across border officials at Europe's busiest airport.
Isaac the cheetah was seized by officials when they spotted his identity marker, used to tackle the trade in illegal animals and stop smugglers cheating the system, was missing.
The endangered African cheetah was stopped at London's Heathrow airport as he was being taken to Russia from a safari park in South Africa, the UK Border Agency (UKBA) said.
He will now be re-homed in a wildlife park in the UK until officials find out why his microchip was missing.
Marc Owen, head of UKBA operations at Heathrow, said: "The illicit trade in animals is a serious contributory factor in the threat of extinction faced by many endangered species, and that is why the rules around moving them are so strict.
"Each animal has to be clearly identifiable by a unique marking, for instance a microchip, to ensure they can be tracked and traced, and to prevent them being sold illegally."
Transporting endangered animals without microchips is a breach of the Convention in International Trade in Endangered Species (Cites).
The animal is being held before it will be rehomed
Mr Owen went on: "At this stage we do not know whether this was simply an error or whether there were other reasons for it.
"Isaac has been thoroughly examined and is in good health. He will now be re-homed in a UK wildlife park whilst investigations continue."
Isaac was one of four cheetahs which landed at the airport on December 22. Two female cheetahs were allowed to continue their journey while another male was sent back to South Africa, UKBA officials said.