Between July and August 2007, Lyu entered the plant's refrigeration storehouse and attempted to inject insecticide into the dumplings with syringes, but failed.

He re-entered the refrigeration storehouse three times between October and December 2007 and injected insecticide into six to nine boxes of frozen dumplings.

The contaminated dumplings were sold to Japan and the Hebei's city of Chengde. Nine Japanese citizens and four Chinese in Chengde fell sick after eating the food.

In January 2008, Japanese media reported that 10 people fell ill after consuming frozen meat dumplings produced by the plant.

The Tianyang Food Plant recalled its products and suspended production after the incident, resulting in a loss of more than 5.5 million yuan (about 908,000 U.S. dollars).

Tests showed that the remaining dumplings from the same batch sent to Japan and other batches produced by the company at the time were safe, according to Chinese quality inspectors.

The plant was investigated by both Chinese and Japanese authorities shortly after the incident, but no problems were found.

In March 2010, Lyu was detained by Chinese police.

The Shijiazhuang Intermediate People's Court held a trial on July 30, 2013, when Lyu confessed to the crime in court, saying he felt sorry for the sickened people and did not expect his acts to cause such serious consequences.