A former US Air Force pilot has been cleared of kidnapping and sexually assaulting a nine-year-old girl.

Robert Prussak, 57, approached the girl after she became separated from her family during a trip from France on April 22.

The girl, who cannot be named for legal reasons, was standing outside Harrods department store in Knightsbridge, London, a trial at Isleworth Crown Court heard.

Mr Prussak then walked with her to his flat and was accused of giving her bitter-tasting water allegedly containing the antihistamine Benadryl, which left her tired, the court was told.

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Robert Prussak was acquitted at Isleworth Crown Court on Tuesday (Anthony Devlin/PA)

It was alleged that the pilot, of no fixed address, then took the girl to Hyde Park and sexually assaulted her.

Mr Prussak was arrested later on the same day after he and the girl were spotted walking past the Israeli embassy by a Metropolitan Police officer who had been informed she was missing.

He was searched and said, “I was just trying to help her out”, according to Sergeant Edward Lucas.

Mr Prussak denied all the charges against him and a jury found him not guilty on Tuesday.

Judge Edward Connell told Mr Prussak, who broke down in the dock as he was acquitted, that he was free to go.

Jurors had asked if there was any DNA evidence of the sexual assault just over an hour after they started deliberating on Monday, and the judge said there was not.

Mr Prussak was found not guilty of three counts of sexual assault of a child under the age of 13.

He was also cleared of one count of kidnapping, one count of committing an offence of kidnapping with an intent to commit a sexual offence, and one count of administering a substance with intent.

On Tuesday, the Metropolitan Police arrested a 57-year-old man at Isleworth Crown Court on suspicion of possessing indecent images of children.

He was taken to a police station and remains in custody.