My question involves divorce in the State of: California

I'm writing this on behalf of my mother. In Nov. 2008 my mother found out that my father had taken out a jumbo loan (approximately 500k) from the house. He claimed that he tried to start a business but it failed. Long story short, he runs out and hasn't helped pay for the mortgage since (FYI: Parents bought the house together in 1985). Then around Oct. 2010 he served my mother with divorce papers (FL-110). We responded with a FL-120 form asking for the property but we haven't heard back from him. How do we proceed if we have no clue where he is? We tried getting a lawyer but the prices were just too steep, we are barely staying afloat as is. Thanks for your help!