Updated

LONDON (AP) — The disguised gunman who burst into an upmarket London jewelry store and carried out one of Britain's biggest-ever robberies was sentenced to 23 years in jail Friday, a year to the day after the heist.

Amam Kassaye, 25, was part of a well-organized team that made off with 40 million pounds (more than $60 million) worth of gems from Graff Diamonds' store on London's Bond Street. The glittering haul has yet to be recovered — and insurers have offered a million-pound reward for information leading to its recovery.

Kassaye came into the store and put a gun to the back of terrified shop assistant Petra Ehnar, forcing her to empty the store's display cases and briefly taking her hostage as he and an accomplice ran out into the street.

In court, Kassaye's defense claimed that the Aug. 6, 2009, robbery had not been carried out by him but rather "by someone remarkably like him." But Ehnar identified him as the robber — prosecutor Philip Bennetts told jurors that his facial features "would be etched in her mind forever."

Kassaye and his gang used professional makeup and a series of getaway cars and blocking vehicles to escape police, discharging his weapon to send shoppers and passers-by scrambling for cover.

Three other men involved in the robbery — Solomun Beyene, Clinton Mogg and Thomas Thomas — were sentenced to 16 years each.

All four men were convicted earlier this year. Two others were cleared by the court after the judge ruled they had no case to answer.

Scotland Yard says it is still looking for a motorbike rider thought to have been involved in the getaway.