Underwater video footage shows one occupant visible in the wreckage of the plane which was carrying Cardiff City footballer Emiliano Sala, the Air Accidents Investigation Branch said.
The wreckage of the plane which was carrying the footballer was found in the English Channel on Sunday morning after almost two weeks.
A private underwater search team located the aircraft and informed the families of Sala and pilot David Ibbotson.
David Mearns, who led the privately-funded search, confirmed the plane was identified by sonar off Guernsey at around 9am on Sunday.
AAIB officials arrived at the site to inspect the wreckage and have now issued a statement.
They said: "Having identified a priority search area last week, the AAIB agreed a search strategy with Blue Water Recoveries Ltd to maximise the chance of locating the aircraft wreckage.
"The AAIB commissioned specialist vessel Geo Ocean III and Blue Water Recoveries Ltd commissioned FPV Morven and the search area was divided between the vessels. Both vessels began their search on the morning of Sunday 3 February.
"Early in the search, the Morven identified an object of interest on the seabed using its side-scan sonar equipment. It cleared the immediate area for the Geo Ocean III to use its underwater remotely operated vehicle (ROV) to survey the area of the seabed in which the object was located. Based on analysis of ROV video footage, the AAIB investigators on board the vessel concluded that the object is wreckage from the missing Piper Malibu aircraft, registration N264DB.
"The ROV carried out a further search of the area overnight, but did not identify any additional pieces of wreckage.
"Tragically, in video footage from the ROV, one occupant is visible amidst the wreckage. The AAIB is now considering the next steps, in consultation with the families of the pilot and passenger, and the police.
"The image shows the rear left side of the fuselage including part of the aircraft registration.
"We intend to publish an interim report within one month of the accident occurring."
Sala was travelling from Nantes to Cardiff last month shortly after completing his £15m move to the Premier League side.
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He was on board the the Piper Malibu aircraft private jet when the flight lost contact with air traffic controllers.
Guernsey Police called off the search after four days, insisting the chances of survival were "very slim".
A successful online appeal led to the private search being launched on Sunday alongside a separate Air Accident Investigation Branch search.
"But hey have heard devastating news and in respect of the families I won't comment any further about what has happened."
He admits he felt he was obliged to lead the search after seeing a plea from Sala's sister Romina.
She appeared in front of the press, begging for rescuers to continue looking for her brother.
"I just felt that girl needed help and that’s why I offered my assistance," he said.
"I am a football fan. Cardiff is not my city, but I follow football. I felt very badly for her, I wanted to help. I just happen to be a person with this experience and skill and I could do that.
"To add to it this was a man in the prime of his life. It is just so tremendously sad."