I want to get my coworker fired but how?

Yea it sounds harsh but before you judge let me explain. He is lazy, does not know what he is doing no matter how many times he is trained. He comes to work high from weed. Brings weed to work so he can sell it. I work in a hospital where it is very important that we do our job right for the patients. I have complained to my supervisor about his laziness but it has not changed. I don't mean to be mean but he needs to go. He started off in laundry and somehow got the job as a patient tech. How can I get him fired? And once again before you judge, if you were a patient in the hospital would you want someone who was high and doesn't know what the heck they're doing taking care of you? I wouldn't either. Anyone have any ideas? Thanks.