2001 Ford Focus Engine lock-up

In September while sitting at a stop light the engine just stoppped and wouldn't turn over. The mechanics said the timing belt had broken which they replaced and said everything else checked out. Then a couple of months ago it started cutting out/idling rough by not consistently. I talked to a mechanic who said it sounded like a vacuum leak. On the way to a parts store, while sitting at a stoplight again, the engine died again but with a little more noise and smell than the previous time. This time the engine would turn over but never seemed to fire. After a few attempts to restart, the engine quit turning over and appears to be locked up. I tried to turn the engine forward and backward manually but it won't budge. My questions are, is the engine toast and if so could the timing belt be a cause?