A top cop's schoolboy nephew drowned when he was knocked from his dinghy by a speeding powerboat, a court heard.

Luke Noble, 15, his cousin Stephen, 18 and two teenage American friends were flung into the water when the craft ploughed into their dinghy in the darkness off the British Virgin Islands in the Caribbean.

Luke, of East Boldon, South Tyneside, and his American friend Duncan Campbell-Harty, 19, were killed instantly when the speedboat hit them at head height then disappeared into the darkness.

The pilot of the boat, Dutch tourist Argan Hendrickson, did not stop even as Luke's party had yelled at him to do so, a trial in the British Virgin Islands heard.

Hendrickson denies two counts of manslaughter and one of gross negligence in connection with the teenagers' deaths.

The pair were killed when Hendrickson's boat ploughed through their dinghy in the British Virgin Islands on August 6.

The court heard that British Virgin Islands law imposes a duty to assist in a collision, and even though Hendrickson stopped when asked he stayed only a few minutes then sped off at top speed.

Both victims were knocked out of their dinghy, which was also carrying Luke's cousin Stephen Noble, 18, and another American friend Ian Murray.

Luke and Dennis suffered serious head injuries and lost consciousness, causing them to drown.

Prosecutor Terrence Williams said: "As a seaman Hendrickson was required to stand by after the collision and offer assistance, but even when the boys were begging him to stay, he did not.

"If he had offered early assistance lives could have been saved."

Mr Williams told the court Hendrickson's gross negligence stemmed from the speed he was doing.

"He ought to have gone well below five knots, where a gathering of boats were moored, but he was actually going above 10 knots," he told the court.

Marine surveyor William Bailey who examined the boats after the accident told the court Hendrickson's speedboat the Boston Whaler had not crossed straight over the dinghy because the boat was not scarred by propeller marks.

But from the marks on the 'Whaler, it was clear the speedboat was travelling at least three times the speed of the dinghy, at about 12 to 15mph, Mr Bailey said.

He added that Hendrickson couldn't have been going at five knots as at that slow a speed the boys wouldn't have been thrown off the boat.

Before the tragedy, Luke had been staying with his uncle Det Chief Insp Tony Noble of Northumbria Police who was on a three-year secondment in the Virgin Islands.

Last week Luke's parents, Mark and Karen, flew out to Tortola in the British Virgin Islands, where the trial began last Tuesday.

Luke's uncle, Vince Noble, 39, from Gateshead, said: "We are very disappointed he has only been charged with manslaughter. It means we are not going to get the justice we want to see.

"Luke was taken away from us and there is nothing that can ever be done to change that."

Luke, a pupil at St Joseph's Comprehensive School, Hebburn, had ambitions to become an engineer.

The trial continues.