Six Baltimore police officers have been charged with crimes including second-degree murder, manslaughter and assault in the death of Freddie Gray.

According to prosecutors, the officers bound Gray's hands behind his back, tied his ankles together and left him face-down on his stomach, unrestrained and helpless, on the floor of the van while it careened through the streets of Baltimore. The fatal injuries that Gray sustained allegedly occurred as he slid and bounced off the walls of the van, at one point hitting his head on a protruding bolt. In short, prosecutors allege, his injuries were inflicted by police on purpose.

That is a very different story than the account leaked to the media this week by Baltimore police sources. In that version, a second prisoner riding in another section of the van had told police that Gray had been throwing himself against the walls of the van on purpose, intentionally trying to injure himself. (The second prisoner could hear but not see Gray.)

It would seem very difficult for a prisoner bound hand and foot, laying face down on the floor, to fling himself on purpose against the van walls. Furthermore, the second prisoner has now come forward to contradict that conveniently leaked police document. Donta Allen says that he did hear Gray bounce off the walls and scream for a few seconds, but he had never suggested that Gray was doing it intentionally.

Allen added that after the van reached police headquarters, officers were joking with each that "We gave (Gray) a run for his money." As the Baltimore Sun had previously reported, Baltimore police have a documented practice of using "rough rides" to inflict injuries on suspects.

It's important to note that the officers are innocent until proved guilty and deserve the due process that Gray did not get. But there's another central aspect to this case that cannot be overlooked.

In her statement this morning, Baltimore State's Attorney Marilyn J. Mosby revealed that contrary to their claims, police had no probable cause to arrest Gray in the first place. The pocketknife that police cited as an illegal switchblade, and that supposedly constituted probable cause, was not a switchblade at all and in fact was just a pocketknife, perfectly legal under Maryland law.

The false police report of a switchblade, and the leaking of an apparently false report about Gray trying to injure himself, suggest a much deeper problem, a cultural problem within the Baltimore police department. Yes, it's a scandal when police officers kill and injure people outside the law, but that scandal is compounded when people -- and police officers -- believe that officers will not be held accountable, that they will be protected even if it means that evidence must be hidden or altered. When that happens, it's no longer a case of an officer or two behaving badly. It's a case of the entire department being corrupt.

In this case, without the marches and protests that have forced a much closer inspection of the evidence in Freddie Gray's death, it is exceedingly unlikely that charges would have been filed and that justice would be done. If we do not address this second issue -- if we do not create a system of credible, thorough, outside investigations of alleged law enforcement excesses not just in Baltimore but everywhere -- then it will be much more difficult to address the first issue of police brutality. They are two sides to the same bloody coin.