An Metropolitan Police Department officer arrested this week on suspicion of taking bribes from Daiwa Securities Co. was asked by the brokerage to help halt a 1993 investigation into the firm, police and prosecution sources alleged Friday.It is possible the MPD's investigation targeting an employee at Daiwa's branch in Numazu, Shizuoka Prefecture, may actually have stopped because of the actions of the officer, Takayoshi Hontao, the sources said.The MPD in the end took no criminal action against the firm in the Numazu probe, the sources said. Hontao, 44, a former MPD inspector, was arrested Wednesday for allegedly taking 2.8 million yen in bribes from Daiwa Securities in exchange for leaking police information about a fraud investigation involving another branch in Tokyo.The Numazu probe was a followup to the arrest of the head of Daiwa's Kunitachi branch in western Tokyo on suspicion of swindling three customers out of 2.4 billion yen in securities between October and November 1992. The branch head has been sentenced to eight years in prison.After police began probing the Kunitachi case, fresh suspicions emerged that an employee at the Numazu branch may also have been involved in a scam to which the Kunitachi branch manager was linked, the sources said. The MPD had planned to send investigators to Numazu to search for evidence, but the action was eventually canceled and the suspicions were never followed up, the sources said.Hontao, who was believed to have urged his colleagues to stop their investigation, was part of a team that interrogated the Kunitachi branch manager at the time. Investigators believe that he acted at the request of a Daiwa Securities executive who somehow learned of the imminent police probe into the Numazu case, the sources said.