Tokyo metropolitan police said they arrested Hideaki Kumazawa, 76, on Saturday for attempted murder for allegedly stabbing his son with a knife. On Monday, media said he was now a murder suspect after the man died.

National broadcaster NHK said Kumazawa, a former envoy to the Czech Republic, told investigators his alarm over his son was provoked by news last week of a knife-wielding man who slashed at a group of schoolgirls, killing two and injuring 17.

The suspect in that incident was also middle-aged and rarely left the house where he lived with his elderly aunt and uncle. He killed himself soon after the stabbings.