The victim stopped paying her rent after her utilities (which the rent was supposed to cover) were shut off. The reason the utilities were shut off probably had something to do with the fact that the real landlord passed away. The murderer, who was not the landlord, assumed the responsibilities of collecting the rent, cashing the checks, but not paying the utilities.
Weird story.
In fact, the law probably permitted what she might have done (set aside amounts to cover utilities). This was not just a crooked slumlord, it was an evil crooked slumlord.
So the killer was also a fraudulent landlord....