The following is from Tom Cabeen's Biography
http://www.xjw.com/cabeen.html
I began to make inquiries of various trusted friends in "high places" in the organization to find out what was going on. I obtained a copy of a letter that had been written to the Watchtower Society by Carl Olof Jonsson, a Witness elder from Sweden. In it he presented evidence that the Watchtower chronology was in serious error. The evidence appeared indisputable. Still, the hardest part to accept was not the error of the chronology but the corollary: If the chronology was wrong, the very important Watchtower doctrine of its appointment by Jesus as the "faithful and discreet slave" was in error. They were not what they said they were. Moreover, the leadership of the Society were misled at best, and hypocrites and false prophets at worst. I read and reread the evidence until I was convinced. I was forced to consider the possibility that the Watchtower Society was not who they said they were. When I did, many questions and doubts crystallized in my mind. Many things began to make sense. Although I had thoroughly enjoyed my service with the Watchtower organization, and loved my Witness brothers and sisters dearly, it appeared more than likely that there would be a parting of the ways. I accepted the fact that my career as a Witness was over. I simply lost my desire to continue actively supporting something I could no longer believe in.
I need to find that letter to see just what changed Tom's mind about the FDS