Those closest to NG will hopefully have been extensively questioned about her routines and schedule. Neighbours also, people at her Church and those who zoomed in to SG's church.
Without having that picture, we wise Web Sleuths are missing so much. There was a lot of chat initially about what an 84 year old can do and what they may struggle with. It was often very generic and quite demeaning in some instances. In terms of NG, none of us know exactly how her medical and mobility issues affected her. With my own nearly 80 year old mother who lives alone - I know exactly her limitations and strengths. I do know that this generation is often quite "tough" and enjoy their independence. My Mum, like NG, has lived in her house for a very long time. It's now too big for her, but she won't move and I won't push her on this.
Motives seem to boil down IMO to:
1. To hurt SG or another member of the family (a grudge, a debt?)
2. Money - either from NG directly or in the form of a ransom
3. Robbery - gone wrong - so the aim was to break in and steal.
4. Mental illness and a fascination with either SG or NG therefore a distorted motive.
5. Their moment of fame - knowing that this would be big news given the SG connection.
6. A wider gang related crime, whose motive was to send a message to someone or something?