The question for Vincent Donofrio and Kathryn Erbe in this episode is exactly what the motive was for the death of the victim. It revolves around a wrongful life suit for a young woman played by Alison Pill who has spina bifida and is confined to a wheelchair. She's a smart young woman, but who will need lifetime care for her condition. They used to live well in Manhattan, but now live in reduced circumstances in Queens Village. Her main caregiver is her brother Jonathan Tucker. A simple test by an obstetrician done while the mother was pregnant would have told her that her daughter would have had that condition and she might have chosen an abortion.
I can't say more other than the perpetrator had some long term planning involved. Nice performance by Alison Pill as the person all this action swirls around.