You say he owes you $500 in bills and he gave you a $500 deposit.
Why not try and talk to him and reach an agreement that you keep his $500 deposit to cover the $500 in bills?
Can you prove he actually owes you $500 in bills? If this is for things like utilities, how can you be sure how much he owes when there are three other people living in the home?
Keep in mind you also broke your lease by allowing someone who is not on the lease move in.
You should try and settle this like brother and sister not enemies.
Best of luck to you,
Kawain Payne, Realtor
http://www.dca.ca.gov/publications/landlordbook/catenant.pdf Download and read it. Especially the chapters on Sublease and Eviction. I'd suggest you all sit down together and try to work out come arrangement. If your Landlord does not know your brother is living with you, it creates another problem.
If you can get your brother to agree to leave, maybe you need to forgive the debt and offer him his deposit money back. Cut the losses now. If your brother has no place to go, no income, then its a whole different story. Good luck.
In relation to tenant rights and eviction laws, it may not matter if he is on the lease. You reached a verbal contract, collected a deposit, and have collected monthly rents and utility payments. He probably has tenant rights, same as if he was on the lease.
If you hire an eviction service, it will cost several hundred dollars, but they will know what your options are. But this will take several months and will cost money and it may be uncomfortable to live in the same home with the person you are evicting.
Hopefully you learned a lesson, not to let others move in and establish residency. Most rental leases prohibit this, so you may have violated your lease.
I strongly encourage you to resolve this situation without the eviction service. Be practical. It may be cheaper to return his deposit and forgive his $500 debt if he leaves soon. Make him see the benefit.