If I’m joint tenants with a girlfriend who is violent and committing fraud, can I terminate my lease immediately?
No, unfortunately a co-tenant's violence against you, fraud against you, or her violations of the lease do not allow you to terminate your lease. You can only terminate the lease without penalty when the *landlord* has done something wrong (e.g. violated his/her obligations; not provided habitable living space; etc.). However, the landlord cannot be penalized for what your co-tenant is doing; you don't have the right to terminate the lease and deprive him/her of a renter because of something another person does.You can certainly speak with the landlord, and see if he/she will let you out of the lease. You can try to sublet the apartment to another (if that's allowed) or assign the lease to another person (also if allowed), so you can get out. You should be able to evict an illegal subtenant. You can seek a protective order against the girlfriend; press charges if you've been assaulted or robbed; and may have grounds to sue her (e.g. for the money that's been taken; for medical costs). But you can't terminate your lease because of what she is doing.