"If left alive, he would cost more than that due to his criminal activity over the next few years."

Freddie Gray was a petty criminal with mostly selling drug paraphanalia and weed. He did have a few more serioius offenses but nothing that deserved death.

Perhaps you did not read the dollar amount right. I am guessing that Gray's family will get in excess of $38,000,000 in tax free money. That guess is based on another Baltimore prisoner who was given the rough ride and won an award for $39,000,000. He wound up a parapalgic. Gray died.

...and the cops are not responsible in any way?