As a former prosecutor who believes that police violence is an urgent problem that must be addressed, I read (and watched) with interest the statements made by Hennepin County Attorney Mike Freeman last Wednesday about the ongoing investigation into the killing of Justine Ruszczyk Damond. Among other things, Freeman (who was secretly recorded) said that "investigators haven't done their job" in the case. Somehow, it seems to have made everyone angry at the same time. It shouldn't.

Some were disturbed by Freeman's blunt expression of frustration. To prosecutors and former prosecutors, though, it was familiar. Though this is largely hidden from public view, there is often tension between prosecutors and investigators. Within our scheme of law enforcement, this is a good thing. We want prosecutors to hold investigators accountable and discern the strength of the cases brought to them.

Except in some rare instances, cases don't originate with the prosecutor. Rather, it is investigators who develop a case and then bring it to the prosecutor in the hopes that the prosecutor will accept the case and pursue a conviction. It is the prosecutor's call whether to go forward or not. That is where the tension, a healthy tension, comes in.

Think about: An investigator takes a case to a prosecutor, wanting that prosecutor to bring a charge. At that point the investigator wants to move forward, since she has decided that the case is worthy and she has invested time and energy in it. It is the prosecutor's job to cast a critical eye at the proposed case, and to demand more evidence if it is needed (as it often is) or even decline to take the case further.

My students are often surprised at the way this process works, and even more surprised how often — in some jurisdictions, as much as half the time — the prosecutors will decline to take the cases brought to them by the police. Justice depends on that critical eye, though, and the prosecutor who demands evidence sufficient to convict before going ahead with a charge is something we all should want. That prosecutorial discernment can and does prevent innocent people from being dragged into the system, and it diverts weak cases away from court. As a professor who trains future prosecutors, I am careful to include this important task in what I teach, even doing simulations in which an investigator tries to pressure a student/prosecutor into taking a poorly prepared case.

As you might imagine, that process does create some conflict between prosecutors and investigators. The police may rankle at being told to do more, and especially at having their cases rejected. Given that a prosecutor will work with those same investigators in the future, it takes some backbone to do that part of the job right. Freeman's statements did not peel back the cover on something tawdry; rather, it awkwardly revealed the way the process is supposed to work.

Even with Freeman's statements becoming public, there is much more that we don't know than what we do, and that is appropriate at this stage of an investigation. Trials and sentencings play out in the public eye, which is good; we can see important decisions being made. Investigations, though, cannot thrive if everything is public as the case is pulled together. There are very real dangers to public investigations: Potential witnesses flee, documents are hidden and public opinion can take a premature turn. In an important case, there is a lot to do, and the work builds on what comes before it. Witness statements need to be corroborated, documents must be analyzed and, in some cases, forensic science must be applied before an informed opinion can be reached. At each step, the early read may be the wrong one, and if that shapes the public perception it can be a difficult task to turn it back to the truth that emerged later. Justice almost always takes time, but injustice moves quickly.

I'm sure that Freeman wishes he had not said what he did, since it has created damaging speculation about the case. Still, the brunt of what he did say (somewhat inartfully) was understandable given his role: He is frustrated with his investigators because he needs more information to make an important decision. The troubling thing would be (and too often is) an overeager prosecutor rushing to enter a charge and hoping to please an investigator.

We don't know what the charging decision will be in the Damond case, and praise or criticism should wait until that decision is made. Patience is hard, but almost always worthwhile, especially when the stakes are so high.

Mark Osler is the Robert and Marion Short Professor of Law at the University of St. Thomas.