The body was traced to the undercarriage of Kenya Airways flight KQ 100 that left from Nairobi's Jomo Kenyatta International Airport, Kenya Airports Authority said in a statement Tuesday, adding that it is investigating the incident.
London's Metropolitan Police said Monday that the victim appeared to have fallen from the landing gear compartment as the plane approached London's Heathrow Airport.
One neighbor described hearing a "whomp" as the body hit the ground, the UK's Press Association (PA) news agency reported.
"He had all of his clothes on and everything. I had a closer look and saw there was blood all over the walls of the garden," the neighbor told PA.
Police were called to an address in Offerton Road in the south London neighborhood of Clapham at 15:39hrs (10:39 ET) on Sunday "after a body was discovered in a garden," the police statement read.
Officials are working to establish his identity and "a post-mortem examination will be carried out in due course," it continued.
A bag, water and some food were discovered in the landing gear compartment once the place touched down at Heathrow, the police said.
The Clapham resident said the man landed a meter (3 feet) from a man sunbathing in his garden.
"So I went outside and it was just then the neighbor came out and he was very shaken," the neighbor, who asked not to be named, told PA.
He suggested the victim was already dead when he fell, adding that the stowaway was "so intact... because his body was an ice block."
While the death is not being treated as suspicious, police inquiries will continue.
In 2015, a stowaway on a British Airways plane from Johannesburg fell on a roof during the jet's approach to Heathrow. A second man who was hiding in the undercarriage of the plane was hospitalized with injuries.