If Burke, for example, were to be charged with Misdemeanor Death by Vehicle, he would be held in jail under a bailbond (somewhere in the range of $10,000 to $15,000). If nobody bailed him out, or if his bond was not reduced, he would remain in jail until his court date (probably within 30 days), at which time a hearing to reduce the bond could be held. The judge would not have to reduce the bond, however.
If Burke was charged with Manslaughter, his bond might be $100,000. That might explain why Burke was still locked up.