Complex sentence: Of the original 75 refugees who attempted to cross the border on September 30,2006,17 remain unaccounted for, either because the Chinese government would punish them if they spoke out or may have died during arrest, torture and detention.
Split into simpler sentences: Of the original 75 refugees who attempted to cross the border on September 30,2006,17 people remain unaccounted for. This may be due to the fear of the Chinese government punishing them if they spoke out or they may have died during arrest, torture and detention.