A 30-year-old graduate of Osaka Metropolitan University was arrested Tuesday for allegedly stealing sodium cyanide from a lab at the university's Sugimoto campus in the city of Osaka.

The suspect has admitted to the allegations against him, saying that he stole the poisonous compound to kill his father, according to the Osaka prefectural police.

The man is suspected of stealing sodium cyanide from the lab of the public university's graduate school of engineering in early August 2023. The police have not found the stolen substance yet.

After enrolling at the university's graduate school in April 2022, the suspect completed his studies in March this year. He works at a pharmaceutical company.

The man has admitted to stealing the substance by putting the contents of a bottle of sodium cyanide into a bag while he was a student at the school. However, he said that he threw away the substance without using it on anyone.

None of his family members have reported feeling unwell, according to the police.

On May 16, the university announced that a bottle of potassium cyanide and a bottle of sodium cyanide, enough to kill around 160 to 250 people in total, had gone missing from the lab. Suspecting that the bottles may have been stolen, the university on May 17 filed a theft report with the Osaka police.

The man told police investigators that he also threw away the two bottles reported stolen by the university.