ITA. Reading everyone's great thoughts in this thread is rather creeping me out this morning. I'm left feeling that between the arsons and the alleged poisonings, MH was a classic revenge killer in the making. You cross her and she'll get back at you.
MH will be a case study for sure.
http://www.trutv.com/library/crime/criminal_mind/psychology/widows/2.html
(snip and overall good article at the above link)
Revenge Killers are typically obsession-driven; hate or love or jealousy are the most common factors. They are as rare as sexual predators but, when pushed, they strike with a vengeance. While many female killers are usually much younger the average age is mid-20s to early 30s Martha Wise of Ohio committed her crimes at the age of forty. A spinster when she found her true love, she was overjoyed. But, her family objected to her choice, as did her minister. (Her beau, Walter Johns, was a much younger man.) In revenge, she fed three of the more vocal family members a deadly dose of cyanide and torched the church. When apprehended and her crimes became public knowledge, the press dubbed her "Lady Borgia of America" after the infamous Italian noblewoman whose actions she emulated. Wise told the judge that the devil made her do it, but the State of Ohio, being unable to catch the devil, threw the total blame on her and locked her away for life.