Our Ford Escort is making creaking noises and the brake and tail lights aren't working. What could be wrong?

About a month ago, the car started making sporadic creaking noises when you press on the brake and it is going pretty slow. We had the brakes checked out and the mechanic said that they were okay, and that the noise was just "road noise". Then about a week ago, one of the brake lights went out. When we went to replace the brake light we found that one of the tail lights had gone out and both of the brake lights were out. When we put a replacement bulb in both of the brake/tail light sockets, the lights stay on indefinitely, even with the car off. They do not get any brighter or dimmer when you step on the brakes. The turn signals are still working. I checked the sockets, and they do not seem to be corroded. If the fuse was not working, wouldn't the lights not work? We are very confused. Any suggestions would be appreciated.