A Cambridge University student who plunged to her death from a light aircraft in Madagascar “jumped” from the plane, police have said.
Alana Cutland, 19, from Milton Keynes in Buckinghamshire, died last week, but her body has still not been found.
Police Colonel D’y La Paix Ralaivaonary told the BBC she “fell into a crisis” which involved “paranoia”.
He ruled out any connection to malaria drugs and said: “It is confirmed that she opened the door and jumped.”
The investigation into why Ms Cutland fell from the plane is continuing, but one theory was that she may have suffered a severe adverse reaction to anti-malaria drugs.
The colonel said: “We haven’t heard about malaria drugs.
“We investigated but… she had problems. She fell into a crisis – paranoia.”
The incident was “not connected with drugs”, he added.
Student Ms Cutland was studying natural sciences at Robinson College and was on an internship on the African island at the time of the incident.
Another police colonel, Jafisambatra Ravoavy, told the BBC she had opened the door of the plane soon after it took off from a remote airstrip in northern Madagascar, on 25 July.
Col D’y La Paix Ralaivaonary said there had been a struggle on board and another female passenger had tried to stop Ms Cutland jumping, “but wasn’t able”.
The passenger was now being supported by the British Embassy in the island’s capital Antananarivo, he said.
Both she and the pilot have been interviewed by police.
Officers are today visiting the hotel where Ms Cutland was staying, he added.
The cause of her death has not been confirmed by UK authorities.
In a statement released earlier this week by the Foreign Office her family said they were heartbroken at the death of “a bright, independent young woman”.