THE sister of a woman accused of murder visited the woman's co-defendant more than 20 times in prison and acted as a go-between for the pair, the High Court heard yesterday. A seven-man jury trying two people for the murder of Cathay Pacific air stewardess Ms Brenda Wong Tze-kwan will retire on Monday to consider its verdict after Mr Justice Duffy sums up the case. Counsel for the prosecution and defence will make their final submissions today. Patrick David Wong, 36, an American citizen, and Kitty Yu Mo-ling, 30, have denied murdering Ms Wong in May 1989. They are being retried. The last witness called by the defence, Ms Grace Yu Mo-shan, a clerk, said she first met Wong in 1988 when she went to his flat with her sister, Kitty Yu, to play mahjong. The second visit was when he was in prison. She stopped visiting him in 1991 because she felt he was using her by asking her to buy him toiletries. She received letters from Wong and admitted that some contained messages for her sister which she relayed. Besides toiletries, Ms Yu said she bought Wong a suit and a pair of leather shoes costing in total $4,000. Further she deposited $55,000 in the account of Wong's friend at his request. Asked where the money had come from, Ms Yu said her sister had authorised her to sell a flat for her. A share of $180,000 was received and it was this money that Kitty Yu asked her sister to use. Wong gave Ms Yu the name of his friend, Cheng Ming-chu, and the bank account number into which the money was deposited. Ms Yu said Wong had told her the reason for the transaction but she could not recall it. Ms Yu said that in the summer of 1991, she relayed a message from Wong to her sister asking her to write a letter to the US Consulate. The letter was to contain the ''old story'', but Ms Yu said she did not know what that meant although she believed it was a secret phrase. Ms Yu said Wong told her that since he was an American, if she sent the letter to the consulate he would be defended and would get out of the charge. She said Wong claimed he could also ask the authorities for compensation, which he would use for her sister's defence. The witness said she passed this message to her sister and her sister wrote to the consulate - a letter which Ms Yu delivered. Asked if she knew what charge her sister faced, Ms Yu claimed she did not know why her sister was arrested and did not discuss it with her. Later she admitted reading about it in the newspaper. She said the newspapers said a woman was murdered and her body was put into an aluminium trunk into which corrosive acid was poured. But she said she never discussed the case with her sister. She also said she did not broach the subject with Wong but he protested his innocence to her. Ms Yu denied a suggestion that she was telling a story to help her sister at her sister's prompting. Asked if on her visits to the defendants in prison they showed any concern for the deceased, Ms Yu said Wong mentioned nothing but her sister said, ''the three of them had received such good education yet the three of them had the same miserable experience - it was such a waste''. The witness said she did not understand this and did not ask her sister to explain.