The inquest is hearing from the Detective Inspector from the Standards Department at the Met Police who says there is no evidence to back any of the claims.
The Professional Standards Detective tells the inquest jury that when the anonymous letter was sent for forensic examination, DNA was found on envelope. Billion to one chance DNA belonged to the unnamed defendant, jury is told.
More top news
Officers were given the touching letter at Brixton Station while they were on a reassurance patrol after yesterday's attack
The 52-year-old had previous convictions for violence but was not on the anti-terror watchlist.
In a statement Charlton Athletic said: Keith was a true hero who will be greatly missed by all the Charlton family and everyone at the club.