Mother Alienation - What do we do now?

It's been a little over three years since my husband and I have seen my step-son. We have gone through every court imaginable. We have go through the Department of Children Services and now our son is missing. Were were granted 50/50 and his birth mother showed up the first few visitations and then disappeared. We have gone back to the courts to try to file the necessary paperwork but no one can help us serve them because we do not know where she is. The police say to go to the courts. The courts say to go to the police. No one is willing to help us. We exhausted our life savings in all the inital court proceedings. We do not have the money to hire a new attorney. We dont know what to do. Please direct us! Are thier any lawyers out there that take pro-bono work on these types of cases? Any private detectives willing to work for a low fee or payments? Anything???? Please Help!