A 67-year-old millionairess was arrested Wednesday on suspicion of poisoning her husband with cyanide as it emerged six former partners had already died, in Japan’s latest apparent “black widow” case.

A notorious Japanese serial killer known as the “Black Widow” has died on death row while awaiting execution for poisoning multiple elderly men with cyanide to get nearly $9 million in inheritances.

A Japanese court Tuesday sentenced to death a one-time millionairess dubbed the “Black Widow”, who tricked elderly lovers into drinking cyanide and pocketed millions in insurance payouts and ...