A civil engineer alleged to be at the center of a trial-fixing ring, which illegally obtained repossessed properties that were due to be auctioned by banks, was arrested yesterday, police said. The 53-year-old suspect was taken into custody after allegations that he threatened a witness in the case after he refused to alter his testimony. The engineer has been charged with threatening the use of force and illegal possession of explosives and is due to be tried today. Sources said that the engineer was allowed out on bail last week after appearing in court on tax-dodging charges related to a different matter. Authorities are also said to be investigating the role of a former financial crimes squad officer, three policemen, a Finance Ministry employee, two serving judges and one former justice in connection to the ring that allegedly used forged papers to take possession of valuable properties over which its members had no rights.