Crank no start, engine or timing chain?

I drove to the store and, when I left the store, the car cranked but wouldn’t start. I had it towed to a shop. The mechanic called me the next day and said that the engine had no compression and needed to be rebuilt or replaced. I asked hot that was possible and he asked me if it had been running hot or while low on oil. I spoke to another mechanic who said that it may only need a new timing chain. Is it possible that the first mechanic was mistaken, and that the engine doesn’t need to be replaced?