Questions are being asked after a woman, who had been detained for the 2005 manslaughter of her own mother, was let free and went on to kill a stranger in the street.
Nicola Edgington was today found guilty of murdering grandmother Sally Hodkin with a knife in Bexleyheath in October 2011 as well as attempting to murder another woman, Kerry Clark.
But hours before the attacks, Edgington had phoned emergency services from a Woolwich hospital and warned them she was dangerous. Ronke Phillips reports.
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In a wide-ranging Peston on Sunday interview, he said Parliament security needs reviewing and the PM's counter-terror strategy is flawed.
The terror attack carried out by Khalid Masood at Westminster that left four people dead lasted less than two minutes say police.
Two knives were found at the scene in Islington, North London, and the suspects fled on foot before being arrested.