A Nagoya University student who says she killed an elderly woman found dead in the 19-year-old's apartment has also admitted poisoning a former high school classmate, investigative sources said Thursday.
Suspicious chemicals were found in the student's Nagoya apartment.
Suspicion rests on a tweet the student is thought to have posted last year, in which she reported buying toxic thallium and pondered its lethality. Police are trying to confirm whether the chemical is among substances seized from her apartment and are looking into how it was acquired.