Probably the same "credible source" that told them about the vast gang conspiracy to kill cops.
Not holding my breath on that, see no reason to believe this either.
No doubt in my mind that the DA offered this kid a sweetheart deal to provide this "revelation".
What's funny is that the same people who are taking this "admission" as Bible truth would be the first to discount anything this kid said if it went against the police.
There are dozens of witnesses, and note that none of them are sitting in prison so by "conservative" standards typically a lot more credible, all along the route from the time of Gray's arrest 'til the time he was delivered to Shock Trauma who have given accounts of police abusing Gray and none of those accounts are being bandied about by those who support big government jackbooted oppression.
But one skell sings like a canary to beat a charge and it's like the gates of heaven opened up and God told you Gray was being a rascal.
If it weren't so pathetic, and so transparent, it would be funny.