The book I mentioned is by David J.Borrett, written in 2005, ISBN 0 903755 21 1 There's a Banks family in it, Thomas Alexander, born Andover in 1823, named after his father Thomas and his grandfather Alexander, Emma Banks daughter of Thomas Alexander, and Emma, wife of Thomas Alexander, and Elizabeth, unmarried sister of Thomas, and Elizabeth Snr mother of Thomas Alexander.
Thomas is a suspect for the murder, but in the conclusion of the book "Thomas Banks' part was never more than a minor one" It's a fascinating book.
I hope this all makes sense!
Hampshire Grandma