James,
No DUI because there is no way to legally prove in a criminal court that of impairment. Drug tests might still show the presence of some drugs but again, in a criminal case it will almost be impossible to prove the person was stoned that night. Cell phone records might show if the person was on a cell phone talking or texting.
But, the driver did leave the scene and failed to render aid. The driver left a human being to die on the street. Not even dogs get that treatment.