Police raided the headquarters of Toyo Tire & Rubber Co., its subsidiary and two other relevant businesses for alleged fraudulent labeling in connection with a data falsification scandal, investigative sources said Thursday.

A string of incidents involving 154 facilities that installed substandard earthquake shock absorbers nationwide has developed into a criminal case.

A spokesman from Toyo Tire said, “It is a fact that the company was investigated on March 23, and we solemnly cooperated.”

The Osaka Prefectural Police confiscated several hundred items during the raid in what is understood to precede a full-fledged joint probe with the Osaka District Public Prosecutor’s Office.

Police are set to interrogate workers at the Osaka-based company, its Tokyo-based subsidiary Toyo Chemical Industrial Products Co. and other companies to which the two firms have shipped products. They suspect the group purposely used false labels and shipped substandard earthquake shock absorbers in violation of the Unfair Competition Prevention Act, the sources said.

According to a criminal complaint accepted by Osaka police and prosecutors and other information, the subsidiary allegedly delivered 19 shock absorber units in September 2014 to the Hirakata Neyagawa Fire Department in the city of Hirakata, Osaka Prefecture. Accompanying documents included false results of performance assessment tests that the firm claimed had cleared national standards.

According to a report by Toyo Tire’s independent investigative team, four workers at the subsidiary directly manipulated data, while other workers, including those at the parent firm, are also suspected of being indirectly involved with the falsification.

Police and the Osaka prosecutor’s special investigative squad aim to single out the individuals involved and establish whether they can pursue criminal charges against management, the sources said.

The criminal complaint was submitted by a member of the Hirakata city assembly between February and March, seeking corporate criminal liability and specifically naming Toyo Chemical Industrial Products. The complaint did not specify any individual.

The Unfair Competition Prevention Act prohibits labeling and selling products that may lead to false recognition of quality, content, amount and other elements.

Offences can be punished by up to five years in prison or a fine of up to ¥5 million, or both. Businesses found breaking the law can be punished by a fine of up to ¥300 million.