The Help question

Short plot anybody know the book title, please
drama fiction novel about an Englishman/lord accused killer who is hidden out by a single woman and orphan her children. She is a portrait artist, broke, and has an elderly man and woman help. Children are obtained from jail by bribing the local sheriff. The killer is innocent and as it turns out was set up by the woman's long-time fiancee as I recall.
Sidebar:
The kids wreck a jewelry store /pawn shop trying to steal a ?? diamond to help pay for the woman's expenses.

Thanks russ