Baron had been paired with his handler for the last four years. Essex Police says they had made many arrests together:
He was injured and taken immediately to a veterinary practice but sadly he had to be put to sleep.
The circumstances surrounding this tragic incident are currently being reviewed.
Baron's handler and family are understandably very upset.
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George Osborne told MPs London would shoulder a large part of his 37% reduction in transport funding.
The prison was originally opened in 1852 as a mixed prison before becoming the first female-only local prison in England in 1902.
The victim was travelling between Seven Sisters and Highbury and Islington when she was assaulted.