Un... depending on the interest for this, I'll jump in. 
I'm interested in playing Ms. Springate, the sweet, oblivious upstairs renter who hears Mr. John scream in protest of his murder.

I'm considering playing around with the idea that the young woman was somewhat being courted by Thomas Billings before he moved in. She, in fact, was the reason why he decided to inquire about lodging there. It was a good coupling, but the seductive ways Catherine held against him easily forced his eyes away from Ms. Springate, and before she knew it - he was no longer courting her. In fact, she rarely saw him except on short occasions between leaving and entering the homestead. She had no idea he was having a dual affair with Catherine. Catherine herself informed her that Thomas Billings was her son, which cleared Springate's suspicions that she had stolen her man. She figured the two had reconnected with each other and he was just managing his duties as her son to aid in his family's affairs. Of course, she's chit-chatted with Catherine countless times, believing barely anything that falls from that woman's spoiled mouth; so she would have her doubts about a lot of things going on under the floorboards of her apartment. But this... THIS is nowhere near to what she'd thought was going on.

The reason I would choose to go this route is that it's stated in the histories that Springate was also arrested for John's murder but later cleared. Having a connection with the family, more than being a renter there seems more of a legit reason for them to suspect her. This would also allow for more character interaction, story building, and conflict - cause really, Thomas B was courting her and suddenly decides to take his illegitimate mother instead? Yeah, that's a story there! I can make Springate more of a nosey neighbor who suspected that Catherine was stealing her man - only to find out that they're related... and THEN see that they were having relations! She can become the catalyst to suspicion before the murder happens - almost becoming a victim herself as she tries to get the Constable to realize that she's not going crazy, and she's not a jealous loser; something's not right in that household! Her snooping puts her in danger. 

So, brainstorming aside, if this becomes a thing, then I'm in! Let me know, and I'll create my sweet, damsel Springate.