sir help please

Gud morning to all, Sir I'm an advocate and presently dealing with a case. Sir in my case my client's son has committed suicide by leaving a suicide note. sir SHO never give this suicide note to handwriting experts but on the on pretext or the other he calls my client to give him handwriting sample. Sir it has been now one and a half year FSL report has not come. I contact to FSL and they said that SHO never give them suicide note for analysis. Sir what to do now. Can I go against SHO? If yes under what provisions of law. Kindly help.