When he wrote about a new life, and was forced to step into another world, his progressed Sun was moving to the next sign (from Aries to Taurus), trine Mars (the symbol of the soldier). Progressed Venus inconjunct Uranus and semi square Sun.
When he was released the Sun was opposite Pluto in the progressed chart with progressed Sun trine Neptune. In the natal chart Sun is inconjunct Pluto and square Neptune. Transit Pholus conjunct his Uranus and transit Pluto conjunct Mars completes the picture.
A progressed Sun changing sign indicates a change in life style. When it happened to me, that was clearly so. Sun-Pluto transits and progressions point at periods of stress, survival and comebacks and sometimes of life at stake. It seems the Berghdahl's timeline is corresponding with the transits and progressions with his chart.