The prosecutor has to be convinced that negotiating the agreement is in the public interest and appropriate in the circumstances, and then there are a series of factors the prosecutor has to consider in determining whether that's the case. There are the circumstances in which the act or omission came to light. Did they disclose proactively or did they hide their conduct? There's the gravity of the omission, whether corruption was rampant throughout the senior ranks, and whether the organization has taken disciplinary measures against the individuals who caused it. There are a whole bunch of factors they would have to take into account in arriving at the determination that it's in the public interest, and they are under no obligation to offer this when it's at their discretion.
On May 8th, 2018. See this statement in context.