Tokyo police have sent public prosecutors papers on three people involved in criminal investigations into machinery maker Ohkawara Kakohki on suspicion of making, using and destroying documents containing falsified information.

The Metropolitan Police Department sent the papers Wednesday after receiving a criminal complaint that its investigations into the Yokohama-based company over spray dryer exports were illegal.

Sources said that the three suspects were allegedly involved in compiling a May 2019 report on experiments on the Yokohama-based chemical machinery maker's spray dryer, deliberately excluding data unfavorable to building a case.

The three were also allegedly involved in making a former company executive sign a statement of his explanation during interrogation in March 2020, pretending to have modified it as requested by the former executive. They are also suspected of shredding the statement, according to the sources.

The MPD arrested three Ohkawara Kakohki executives in violation of the foreign exchange law in March 2020. They were charged with exporting spray dryers that could be used for the production of biological weapons.

However, the Tokyo District Public Prosecutor's Office ended up dropping the charges against them in July 2021. The company's side filed criminal complaints with the MPD between March and April this year.

The company's side sued the central and Tokyo metropolitan governments for damages in September 2021. The Tokyo District Court ordered the two to pay a combined ¥160 million, but the suit is ongoing at the Tokyo High Court because both sides appealed against the ruling.

On Wednesday, Ohkawara Kakohki released a statement saying that it hopes the prosecutors will investigate properly.