The stowaway who fell from a Kenya Airways plane in London is likely to have been an employee at Nairobi's main airport, a Kenyan official has said.
The plane was flying from the airport in Kenya's capital to Heathrow when a body fell into a garden on Sunday.
The man most probably had legal access to the airport, Kenya's Civil Aviation Authority chief told the BBC.
A post-mortem examination would be carried out and the death was not being treated as suspicious, UK police said.
The body fell a metre away from a resident who had been sunbathing in the garden in south London's Clapham suburb, a neighbour said.
The neighbour, who did not want to be named, said he heard a "whomp" so he looked out of an upstairs window and saw the body and "blood all over the walls of the garden".
"So I went outside, and it was just then the neighbour came out and he was very shaken," he said.
The neighbour said a plane spotter, who had been following the flight on an plane tracking app from Clapham Common, had seen the body fall.
The plane spotter had arrived almost at the same time as the police and told them the body had fallen from a Kenya Airways flight.
Describing the victim, he said: "One of the reasons his body was so intact was because his body was an ice block."
The identity of the individual is yet to be established.
Police believe the victim fell from the landing gear compartment of the plane - where a bag, water and some food were found when it landed.
The director general of the Kenya Civil Aviation Authority, Gilbert Kibe, told BBC Africa that there was tight security at Nairobi's Jomo Kenyatta International Airport.
It was unlikely that an outsider would have crossed the runway, and climbed into the plane without being noticed, he added.
"They do check every part of the airplane, including the undercarriage, the wheels, the brakes, the tyre condition, the wheel well that is above there. They inspect everything. So when those checks were being done, it is not likely that person was there, otherwise he would have been seen.
"So at which point the person gained access, that is the mystery," Mr Kibe said.
Security concerns at Nairobi airport
By BBC Reality Check
The discovery of the stowaway who started his journey from the Jomo Kenyatta International Airport in Nairobi has raised questions about the effectiveness of security checks in place there.
The airport is already under a state of heightened security largely responding to the threat posed by the militant group al-Shabab, based in neighbouring Somalia.
A similar incident took place in 1997 when the body of a young man was found hanging in the nose-wheel bay of a British Airways flight from Nairobi after it landed at Gatwick Airport.
The Kenya Airports Authority (KAA) says a team has been assembled to investigate how the stowaway got on board the plane.
The KAA carries out security drills at the airport - most recently in November 2018.
It is not the first death of this kind on the Heathrow flight path.
In June 2015, one man was found dead on the roof of notonthehighstreet.com's headquarters in Richmond, west London, while another was found in a critical condition after they both clung on to a British Airways flight from Johannesburg.
In August 2012, a man's body was found in the undercarriage bay of a plane at Heathrow after a flight from Cape Town.