Speedboat killer Jack Shepherd has lost a Court of Appeal challenge against his conviction for the manslaughter of 24-year-old Charlotte Brown.
He was sentenced to six years in jail over the death of Ms Brown, who was thrown from his boat when it capsized on the River Thames during their first date in December 2015.
The 31-year-old web developer challenged his conviction for manslaughter by gross negligence at the court in London last week.
His lawyers argued the conviction was unsafe because some of the evidence at his trial came from an interview during which he was not cautioned or offered a solicitor because of a "mistake" by police.
But his appeal was dismissed by Sir Brian Leveson and two other senior judges on Thursday.
Speaking outside court after the ruling, Charlotte's twin sister Katie Brown said: "We are relieved as a family that Shepherd's appeal against his manslaughter conviction has been thrown out and justice has prevailed.
"My sister Charlie is not here with us today because of Shepherd's negligence and reckless actions.
"He hasn't once shown any remorse or respect to our family, or to the legal system, or to even Charlie."
Shepherd, originally from Exeter, went on the run ahead of his Old Bailey trial and was convicted in his absence in July 2018.
He was later extradited to the UK from Georgia after handing himself in to police in the capital Tbilisi in January.
Jurors at Shepherd's trial heard that he and Ms Brown, from Clacton-on-Sea, Essex, had been drinking champagne and went for a ride in his boat past the Houses of Parliament.
Shepherd handed the controls to Ms Brown just before it struck a submerged tree and overturned, tipping both of them into the cold water.
He was plucked from the Thames alive, but Ms Brown was found unconscious and unresponsive.
Following his return from Georgia, Shepherd appeared at the Old Bailey in April and was sentenced to an additional six months for breaching bail.
The Court of Appeal quashed his bail conviction and sentence on Thursday, but said he may face further proceedings in relation to his "egregious breach".
He was jailed for a further four years at Exeter Crown Court earlier this month after he admitted wounding with intent in relation to a drink-fuelled attack on a barman.
The court heard he struck former soldier David Beech with a vodka bottle on March 16 2018 after being asked to leave The White Hart Hotel in Newton Abbot, Devon.