a. It was possible for them to have escaped.
Does that mean
1. It was possible for them to escape We don't know if they did or not.
2. It was possible for them to escape, but they didn't.
or
3. It was possible that they had escaped. (At time T, it was possible that they had escaped at a time before time T).
and how about
b. It is possible for them to have escaped.
Does it mean anything?