Webster, 54, was jailed for a minimum of 30 years for murdering his first wife Claire Morris in a faked car accident in 1994.
He was also convicted of trying to kill his second wife, Drumm, in a similarly staged car crash in New Zealand five years later.
Webster, a former nurse from Surrey in England, stood to become a millionaire thanks to the life insurance payouts from his first wife's death.
A 2011 trial heard how Webster drugged his first wife Ms Morris, 32, just eight months after their marriage and drove his car off the road with the unconscious woman inside.
He then torched the vehicle and covered his tracks before collecting the life insurance payout and moving to New Zealand.
The jury then heard Webster married Ms Drumm before attempting a copy-cat murder in 1999 near Auckland by drugging her and planning to kill her in another staged smash.
He fled with her lifesavings and returned to Scotland.
There, he tried to con Banarjee into a bigamous marriage, and even getting her to change her will to leave him everything, including her house and a luxury yacht.