Probably not drunk - my first thought - but texting. That’s not that hard to determine, although phone companies are now refusing to release this data, so it might be slower. There was somebody else in the vehicle, too, so i assume they’re interviewing this person.
The mother is right, though; he obviously didn’t just have a mini-sleep at the wheel, such as somebody with diabetes or even just tiredness might have, but he wasn’t paying attention for one reason or another, possibly texting or possibly on the phone with his boss, or whatever. So that should be at least negligent homicide or some such thing. It makes other drivers a little more attentive, if nothing else.
Based on my own experience; I’d say it’s not likely the driver just wandered off the left side of the road and drove all the way across the grass median into oncoming traffic. If driver distraction or inattention was the cause here, a more likely scenario is that the driver wandered off the RIGHT side of the road and over-corrected when steering back to the left.
After Carpenter decided a few weeks ago, the cops might need a search warrant instead of just a subpoena.
https://www.supremecourt.gov/opinions/17pdf/16-402_h315.pdf
People are doing lots of things on their phones these days while driving; plugging in map directions, changing their Pandora station, downloading music from iTunes, trying to find the cheapest gas station. I'm shamefully guilty of doing all four. Lots of distractions.