The suspect, identified as Toshiki Abe, has worked at the Oizumi plant of Maruha Nichiro Holdings subsidiary Aqlifoods Co. for eight years. NHK reported that he went absent without permission on Jan. 14 and was taken into custody in Saitama Prefecture on Friday.

Police allege that Abe, who worked on the pizza line at the factory, brought the pesticide malathion into the plant and used it to taint frozen food products such as pizzas and croquettes, four times between Oct. 3 and Oct. 7, 2013.

Abe was quoted by police as saying he doesn’t remember anything about those four days.

NHK quoted a co-worker as saying that Abe would often complain about low wages at the plant.

Police have not yet determined how the suspect might have brought the pesticide into the plant. Workers change into overalls with no pockets before they enter the production area. Police have been interviewing factory personnel since Jan 8.

In all, nine frozen food products were tainted. Health officials said Saturday that since last October, 2,843 people in all prefectures reported mild symptoms of vomiting, cramps and diarrhea, after eating the tainted products.

Aqlifoods received the first of a series of complaints on Nov. 13, with a customer saying its frozen pizza smelled like machine oil. But the firm did not announce a product recall until Dec. 29, after tests found traces of malathion.

Aqlifoods has recalled 6.4 million potentially tainted products. None of the products in question had been shipped overseas, the company said.