Some experts questioned why Officer Wilson — nominally the defendant in a process aimed at determining his guilt or innocence — had been among the first witnesses to testify, the reverse of usual grand-jury procedure. The move, they said, might have helped establish Officer Wilson’s testimony as the dominant narrative of the case.

“In my experience, it’s quite unusual to put the officer’s testimony first,” Rory Little, a law professor at the University of California, Hastings, and a criminal lawyer who spent eight years as a federal prosecutor, said in an interview. “Normally, if you are going to have the target testify, you bring him in last so the grand jury can compare what he says with everything else they’ve heard.”

But the view that the process might have worked against an indictment, wittingly or unwittingly, is not unanimous.

“You could argue that it was to the target’s disadvantage to testify early,” said Paul G. Cassell, a University of Utah law professor and former federal judge, referring to Officer Wilson. “He’d be locked into a set of statements, and the grand jurors might later find inconsistencies.”