Spoiler space
Considering the hell Jane must have gone through with Quin we must ask the following questions
Why didn't she tie Quin up and gag her?
Why didn't she drown her in the bathtub?
Why didn't she lock her in basement?
Why didn't she just throw her out?
Answers
Quin would have eaten through the gag.
Quin probably takes showers.
No working lock.
Jane is a nice person.
Any other answers?
Mark