The father of a woman who died in a River Thames speedboat crash has warned the fugitive owner that “justice is coming” for him.An international manhunt is under way for Jack Shepherd, 30, who is wanted over the death of 24-year-old Charlotte Brown. It is believed Shepherd might be hiding in a resort on the Mediterranean.The web designer faces six years’ imprisonment over the December 2015 incident, when his speedboat capsized during a late-night cruise after a champagne-fulled first date.Shepherd, who was convicted of manslaughter by gross negligence at the Old Bailey after a trial in his absence, has ignored repeated pleas by Ms Brown’s family to hand himself in.Her father, Graham Brown, 52, urged anyone with information about his whereabouts to contact police. In mobile phone footage, Ms Brown could be heard shouting that they were going “so fast” as Shepherd drove at more than double the 12 knot speed limit. The family of Charlotte Brown (left to right) father Graham Brown, sister Katie and mother Roz Wicken arrive at the Old BaileyCredit:Yui Mok /PA In the months before Ms Brown’s death, Shepherd had entertained up to 10 women on the 1980s model, having invited them back to his houseboat.During that time, he had been caught speeding by marine police more than once and advised on the importance of wearing life jackets. An arrest warrant was issued after his conviction on Friday. On the return journey, Shepherd handed over the controls to business development consultant Ms Brown, who followed suit and went “full throttle”.The speeding boat hit a submerged log and tipped over near Wandsworth Bridge, sending both occupants into the water.Shepherd was found clinging to the hull and Ms Brown was pulled from the water unconscious and unresponsive.Paramedics battled in vain to save her as she was already in cardiac arrest and suffering from hypothermia.The court had heard how Shepherd bought the 14ft Fletcher Arrowflyte GTO from Gumtree to “pull women”. Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings. Charlotte Brown met Jack Shepherd on a dating websiteCredit:Metropolitan Police A picture shown to the jury of the speedboat that crashedCredit:PA “Those who know something need to examine their consciences,” he told The Sun. “I’m sure someone will make that call. Justice is coming, of that I’m certain.”Shephed met Ms Brown on website OkCupid and went for their first date on December 8 2015.He treated Ms Brown to a £150 meal at Oblix in the Shard, where they drank two bottles of wine.The couple took a taxi back to Shepherd’s home, a houseboat in Hammersmith, where they took champagne aboard the speedboat for a trip past the Houses of Parliament.