I think you can sue the government or the individual. I'm not sure where or how it should be filed. I was going to sue the government once for wrongfully putting me in jail. As I remember, you only have six months to file that suit. Part of the reason I didn't do it is the damages for spending a night in jail are not usually that high. The juice wasn't worth the squeeze. This question is really not a criminal law question, to get better help post this question in the civil rights section.
One can be arrested by a "citizen" for either a misdemeanor or a felony.
Your friend may or may not have a law suit. Need to see an attorney in person with all of the reports etc.
The above is not intended as legal advice. The response does not constitute the creation of an attorney client relationship as this forum does not provide for a confidential communication.
If the arrest and detention was without probable cause and you can get past immunity issues you need to file a claim under the Government Tort Claims Act.(180 days).
You need to consult an attorney to evaluate your claim.