ALEX Tsui Ka-kit had concealed a relationship with a man he had repeatedly told his superiors was ominous and undesirable, causing the ''gravest doubts'' on his integrity, ICAC chief Bertrand de Speville said yesterday. Breaking five months of silence, Mr de Speville listed under oath a string of dubious associations and misconduct by Mr Tsui, who as deputy director of operations was the highest ranking local officer in the Independent Commission Against Corruption. Mr de Speville told legislators that he was left with no choice but to sack Mr Tsui immediately. ''Far from providing satisfactory explanations, Mr Tsui's replies and his demeanour caused the gravest doubts about his truthfulness, his trustworthiness and his integrity,'' he told the first day of the historic Security Panel hearing into the dismissal, which has raged as a public dispute between Mr Tsui and the ICAC. He described the sacking as the ''saddening'' downfall of a clever, highly-regarded officer whose ''excellent future had slipped off the tracks''. Mr de Speville said any of his six predecessors would have done the same thing after that interview on November 9. That interview followed a five-month internal investigation - prompted by outside allegations to Mr de Speville and the Governor Chris Patten. ''There came a point where Mr Tsui felt the normal rules of conduct did not apply to him . . . It is a matter of particular sadness to me,'' he said under questioning. Mr Tsui watched from the public gallery throughout the three-hour hearing with his lawyer Andrew Lam, often smirking but also taking many notes. His wife, Julia, sat outside in a back room listening to the proceedings, frequently crying. Afterwards, all three said Mr de Speville's account was ''a mess'' and ''vague'', failing to link up reasonably with the dismissal. ''I will tell the truth [today],'' said Mr Tsui, adding he was quite ''relaxed'' during the hearing. Mr Tsui had been tipped to become its first local commissioner, yet had breached standing orders, trust and confidence through links to ''undesirable characters'', Mr de Speville said. In a slow, deliberate delivery, Mr de Speville spent 30 minutes detailing an investigation which revealed: Mr Tsui failed to report a meeting with Hong Kong Boxing Association vice-president Henfrey Tin in Macau just hours after Mr Tin was interviewed by the ICAC about a large loan to a prominent triad suspect in a Tsim Sha Tsui shooting. Mr de Speville said Mr Tsui's explanation about someone he now claimed was his good friend and an honest businessman as ''simply not credible''. Mr Tsui had worked with Mr Tin 20 years ago in the Customs Department. Mr Tsui had ''covered his tracks'' about his supposedly severed relationship with Mr Tin despite being reprimanded in 1986 over obtaining a false loan for Mr Tin. Mr Tin had at that time been charged with three counts of armed robbery but was not prosecuted. Others charged for the same offences still remain in prison. In a letter to his boss, Mr Tsui said that his friendship with Mr Tin came to an end in the early 1980s because he had gradually sensed that Mr Tin was going through some changes in his life and outlook which Mr Tsui described as ''ominous''. He went on: ''I also felt it was time our friendship should meet an end. I regret to say that he was a friend in the past. A fact that does not serve myself any credit. Despite getting approval in 1990 to treat Mr Tin on a highly restricted informant basis which meant every contact had to be reported, Mr Tsui got on the board of the Hong Kong Boxing Association and built wide social contacts with him, including trips to Macau and Singapore. Only four reports were logged ending in March 1991. Nothing was reported about a $160,000 donation from Mr Tin to the association. Mr Tsui deflected his underlings in 1990 from investigating a company Mr Tin worked for and which was owned by Hung Wing-wah - later to be association president - using an internal memo listing other suspects. Mr Tsui ignored protocol to send a letter containing allegations against a consulate officer to his Consul General without telling the Commission. Counter-allegations from a consulate official claimed Mr Tsui had offered a bribe of $10,000 to forge the signature of the consul-general in a letter supporting a boxing tournament to the Television and Entertainment Licensing Authority. Mr Tsui initially denied to Operations Director Jim Buckle knowledge of the letter, approaching the staff member and offering the bribe. However, when a copy of the draft was produced he admitted it was his but has continued to deny the bribe offer. The matter was now closed. ''Certainly his denial initially became an admission later when confronted with the evidence,'' Mr de Speville said. ''If he had candidly admitted this letter I would have taken a very different view of the matter.'' Legislators expressed deep concern at the fact the ICAC had promoted Mr Tsui - to assistant director in 1988 and deputy in 1992 - despite knowing about his links with Mr Tin. Mr de Speville said Mr Tin joined the association board in April 1992 with a different first name, Henfrey (he had previously been known as Sau-kwong), but added that someone in Mr Tsui's position was expected to show judgment and trust. Action was taken ''not before time'' late last year as soon as the full extent of his links with Mr Tin became known. ''We are not omniscient, we are not omnipotent and we are not omnipresent,'' he said. ''We do monitor them but we do not monitor them 24 hours a day. This officer was a very experienced and clever man. ''He took active steps to cover his tracks.'' Mr de Speville said though Mr Tsui had not committed any crimes, he felt he had to go. But steps were taken to get him out of the ICAC while he was under investigation to avoid unfairly suspending him.