Your brother has multiple issues including (1) there is a drug user in his apratment and therefore possibly drugs, (2) the drug user is a thief, (3) he is respnsible for the entirety of the rental payment (unless the landlord has an absurdly forgiving lease).
If the brother cannot immediately get the roommate to move out and substitute another (which would be unlikely) the brother should approach the Landlord before things spiral out of control and state that the roommate has stolen from him and that he would like to help in evicting the other party. He may well lose the apartment in the process. He should read the lease regarding the loss of his security deposit. He MUST remove things of value from the apartment.
Your brother needs to recognize that, because there are drugs in his apartment, he may be criminally charged as well as the roommate.
Attorney Renda is right on with her response. First, either he needs to review the lease or he needs to have an attorney review the lease. 2nd he should contact the landlord. If that doesn't work, he should contact the police.
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