The suspect in the frozen dumpling poisonings that sickened 10 people in Japan about two years ago and raised anxiety over the safety of foods imported from China, admitted during questioning in early March that he tainted them with pesticide, the Ministry of Public Security said March 28.

The suspect, identified as Lu Yueting, a former temporary employee at the Tianyang Food Plant in Hebei province, stole methamidophos from the factory in summer 2007 and used a syringe to inject the substance into the frozen gyoza dumplings starting that Oct. 1, a senior ministry official said.

The questioning began March 16 and the syringe was found five days later in a sewage line at the factory, the ministry official said, adding that Lu was dissatisfied with the gap between his pay and the salaries of the factory's regular workers, which was the apparent motive for the crime.