I ran across this story a few years back. If you ever seen Arsenic and Old Lace, a movie with Cary Grant – https://www.imdb.com/title/tt0036613/?ref_=nv_sr_1?ref_=nv_sr_1, it’s somewhat different as the reasons for these murders weren’t the same as in the movie. Here’s the quick version, courtesy of Wikipedia – https://en.wikipedia.org/wiki/Black_Widow_Murders.
It does raise the question if there were other deaths aside from the ones they were convicted of.
Here are some other links: