My personal opinion is that NSR has it correct. A smell of alcohol could be something innocent. Raise your concerns diplomatically at first. If this produces no result, you have to get harder. Certainly you must ensure that the guy doesn't fly. But there are ways and other ways of doing this.
The company will not thank you in the least for going straight to the police. You'll get the job done, but not in a manner that will help passenger confidence, help teamwork, help the company image or promote your job security.
LongRange, to go sick yourself doesn't help. Your company will send another FO. He then discovers the real problem, and will either fly or not. If he flies, the initial problem goes uncured. If he won't fly with this guy, then the company needs to send another Captain - and nobody will be happy bunnies. Longer delay, two extra pilots repositioned, extra expense.