Could you please help me with a murder case against my son for witch he did not commit and is innocent

They got him on a murder charge for witch he did not do and they never found a weapon against him in this case and out of the two so called eye witnesses he had had a sexual brief relationship with the waitress's best friend whom was a ongoing patron at the bar it took place at and told them to say it was him out of spite since my son broke it off with her for the woman he had left her for