A POLICEMAN who robbed a businesswoman of $5,000 after threatening her with a replica gun was yesterday jailed for 10 years. Yu Tai-wing, 43, a senior police constable with 20 years' service, mugged factory boss Chan Fung-chu, 43, as she returned to her office carrying $20,000. The officer will now be dismissed from the force and stands to lose his $400,000 retirement payment and his pension. The High Court heard Yu stalked Ms Chan to her office at the Kam Tak Industrial Building, Kwai Chung, after watching her leave a nearby bank. He pulled out a replica Colt pistol and demanded: ''Don't move. Give me the bag of money quickly!'' Prosecutor Jenny Betts said Ms Chan was terrified and threw down an envelope containing $5,000 which Yu picked up. He was caught by several passers-by. Yu, who denied robbing Ms Chan on January 21 last year and possessing an imitation firearm, was convicted on both counts yesterday following a four-day trial. Defence counsel Kevin Chan told the court Yu turned to robbery after accumulating heavy debts. Passing sentence, Mr Justice Leonard said he took into account Yu's lengthy service to the community. He added: ''I'm well aware that he has thrown away his pension and his good name, but that's something he should have thought about before he embarked upon this robbery.'' The judge jailed Yu for 10 years for robbery and five years for possession of an imitation firearm to run concurrently.