Brown, from Clacton, Essex, was fatally thrown from his speedboat boat on the River Thames, when it hit a submerged tree trunk, in December 2015.
Shepherd and Brown had been drinking champagne before he took her on the ill-fated boat trip past the Palace of Westminster.
He was plucked from the Thames alive, but Brown was found unconscious and unresponsive and died later in hospital.
Shepherd, originally from Exeter, then went on the run, and was convicted of manslaughter by gross negligence in his absence after an Old Bailey trial in 2018.
He eventually handed himself in to police in Tbilisi, Georgia, in 2019, and was brought back to the UK where he was also handed a four-year-jail term for attacking a barman, to run at the same time as his six-year sentence.
Shepherd was released in January 2024 and then returned to prison in September 2025, over what was reported at the time as a breach of his licence conditions.
News of his latest crimes first emerged last month in a Parole Board report about his recall to prison.
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