I read this book a few years ago. If I remember right, he played a part in organizing the society in Magdeburg Germany, whose policies were eventually adopted by the Watchtower in the States. I can't imagine that he wanted back into the org at the end of his life. Below I typed part of the foreword of the book.
Foreword
By the Lord's grace I am a Christian. I was found by God in my tender youth. Early in life I was inveigled to join the Watctower Organization, and subsequently became totally enslaved to it.
By the Lord's grace I came free when He lifted me up from a night of prayer, and when I became so agitated and alive once again spiritually that I made a vow unto the Lord. That night I came free!
I have a vow to fulfull, which I made to God, when He set me free, once again to be a Christian: W.J. Schnell