What can we do if son has conspiracy charges?

My son and his friend lived in my deceased mother’s home. His friend hit a neighbor kid with a baseball bat. My son was at the neighbor’s home but did not know it was his friend as the friend had a mask on. They arrested my son and a week later arrested his friend. All the courts have is hearsay evidence but in the meantime, my son has been locked up since November. His friend is being evaluated for mental. There is nothing wrong with the friend. They charged my son with conspiracy and said he is facing 40 years for a crime he did not commit. Do you have any suggestions? My son said he wants a jury trial in hopes that it all comes out.