A Grand Jury failed to indict Darren Wilson, the police officer who shot Michael Brown, which led to riots in Ferguson, MO. This my have been due in part to the fact that the prosecutor presented the Grand Jury with all the evidence rather than just presenting the evidence that bolsters his case for indictment. In this article, Megan Mcardle argues that the prosecutor was in a no-win situation, since he was under political pressure to convene a grand jury, and yet he didn't think that a conviction would be likely. So he intentionally tried not to get an indictment in order to avoid the case going to trial.
But my question is, is it unethical for a prosecutor not to try his hardest to get an indictment after he's convened a Grand Jury? Could a prosecutor be disbarred if it's found that he presented evidence which he knew would undermine his case for an indictment? Would such behavior run afoul of government rules of conduct for prosecutors?