I also got the impression from the the tone of A.B.'s letters that he was remorseful for something. That coupled with hints and stories over the years about Will's family leads me to believe it was related to drinking.
(letter transcribed below)
(click the pic to enlarge"
Note Bernice's reference to no "moon"
1711 Washington Ave
Dec 22nd, 1930
Dear Babe,
We are sending you a remembrance for Christmas. It isn't much but will let you know we thought of you, Hope you get it o.k.
Come out and eat Christmas dinner with us.
I got a 10lb 'Turkey' today. We are having some real winter, the last day or two. Burnett is still working on the Hotel. Come Christmas if you can.
Wishing you a Happy Christmas without any "moon" ha
Regards from Turner Family
Bernice