Kyoto Man Arrested over Murder of University Student with Highly Toxic Element

The Yomiuri Shimbun

7:00 JST, March 5, 2023

OSAKA — A 37-year-old Kyoto man was arrested Friday on suspicion of killing a university student by making her ingest the highly toxic element thallium, police said.

According to the Osaka prefectural police, the suspect, Kazuki Miyamoto, has refused to answer post-arrest questions. The police are investigating how the suspect could have obtained the thallium, among other matters.

Hinako Hamano, a 21-year-old junior at Ritsumeikan University and resident of Kita Ward, Kyoto, died Oct. 15 after being admitted to a hospital.

According to investigators, Miyamoto and Hamano met at Hamano’s part-time job.

Miyamoto is suspected of inducing Hamano to ingest thallium at her apartment on the morning of Oct. 12, causing fatal respiratory failure due to poisoning, the police said.

Prior to his arrest, Miyamoto, a real estate company operator, reportedly told investigators during a voluntary police interview that he and Hamano had gone to her residence after dining together in Kyoto on Oct. 11. He also said that he contacted Hamano’s parents the following day, as she could not stop coughing.

Hamano’s parents took her to a hospital in Osaka Prefecture, but she was transferred when her symptoms worsened, according to police.

The doctor who treated Hamano contacted the police after becoming suspicious about her symptoms, which included vomiting. Following analysis of Hamano’s vomit and urine, thallium was detected. After consulting with experts, the police deemed that Hamano had likely ingested thallium while at home with Miyamoto.

Thallium, a type of soft metal found in nature, is highly toxic. Under the Poisonous and Deleterious Substances Control Law, some substances are designated as deleterious, and their sellers are required to retain written records of purchasers’ names and addresses, as well as the quantity and purpose of each purchase. People younger than 18 are not allowed to buy such substances.

One gram of thallium is lethal for adults. Its ingestion can cause gastrointestinal and neurological damage.