No, they cannot. Sovereign immunity is absolute. US citizens can only sue when granted permission.
As 30thElement noted, the Federal Tort Claims Act grants this permission to sue. But there is no such right, and it is within the Federal government's power to change its mind and repeal the statute.
What were you talking about then? "Suing" is always a civil action. Taking someone to court for a criminal act is called prosecution and can't be done by just anybody.
As 30thElement noted, the Federal Tort Claims Act grants this permission to sue. But there is no such right, and it is within the Federal government's power to change its mind and repeal the statute.