It is not the first time the murder of Debbie Linsley has been re-investigated. In 2002 police thought that they had made a similar breakthrough, giving them the ability to complete a map of the killer's DNA , left behind at the scene.
Here is a news report from 13 September 2002.
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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.