Quote Originally Posted by bitpicker View Post
given a different context,
- Я думал, что они ему поверят.
- Так они ему и поверили.

Provided the stress pattern and intonation of speech is right, the second phrase would mean something like "but that's exactly what happened - they believed him".

"Так" must be unstressed in this case.

I can only imagine it in speech. It looks confusing in writing.

"they did indeed believe him" or "they believed him, too"
You may be spot on. It's just that I'm not sure enough about my English.