Mr Justice Wilkie said Bhayani "ruthlessly targeted" Ms Waugh and murdered her with "greed, callousness and total lack of any regard."
He said: "Without a second thought, you calmly and comprehensively set about stealing her identity" and a complete "asset-stripping of her persona".
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David Webster stole around £1000 a month from her pension and benefit packets until she died in January 2015.
The incident happened in the early hours of Saturday July 16 in a house in the Barnes area.
A Domestic Homicide Review is now set to be carried out after Bennett murdered his current and ex partners