[Poohbah]

are they going to keep trying this cop over and over until they get a conviction?

No, until they get a verdict.

[ambrose]

In a typical case, a prosecutor will only seek a retrial if he believes there's a reasonable chance it will lead to a conviction. With two hung juries, split right down the middle, it would suggest that they'll never get a verdict. If this were not a politically charged case, it would be dropped.