Thanks for your clear and helpful commentss.
Obviously, the criminal case will afford no such opportunity, but in a civil suit for wrongful prosecution, could the plaintiff examine the defendant/prosecutor under oath (specifically, about political pressure to charge, why no grand jury, and the idea you have put forth — whether he/she eschewed a manslaughter charge to avoid the self-defense evidence)? I am sure this is a fantasy. I can’t get beyond a naive fixation on truth and justice, making it hard to stay within the realities of “the law.”
"In order to prove a cause of action for malicious prosecution a plaintiff must prove six elements: '1) the commencement of a judicial proceeding; 2) its legal causation by the present defendant against the plaintiff; 3) its bona fide termination in favor of the plaintiff; 4) the absence of probable cause for the prosecution; 5) malice; [and] 6) damages'."
But, as far as eliciting testimony under oath, yes, he can do that.