Mauro Demetrio told the jury he was arrested after an officer told him he could smell cannabis and that he was driving in a suspicious manner. He alleges that once in the van a fat officer sat on him and that an attempt was made to strangle him.
The court heard a doctor found bruise marks around his neck when he examined Mr Demetrio at the police station.
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The eagle-eyed resident spotted the mistake on signs just feet apart in south London.
The victim was attacked after bumping into a man at the ticket barrier at Putney Station.
The victim, who is his 40s, was found near the edge of palace grounds.