Very sad story. I think the drive should be investigated more, now that there is a death I think the driver is going to go down. That being said.
I have lived in the DC metro area for 13 years now. I run and ride bikes quite a bit. I used to ride my bike to work at 5am. It is not twilight at 5am, it is dark. The people here hate bicycles. I have never lived in an area where the drivers are as mean and agressive as the DC metro area. It is the main reason why I did not buy a tri bike. I did not want to ride on the roads because it is flat out dangerous.
The road she was riding on is a feeder road to the main highway of the DC area. You would have to pay me hundreds of thousands to ride on any feeder road from 5-9 am at the peak of rush hour traffic in the DC metro area with the 2nd worst traffic in the nation. I do not care how many lights or reflectors you wear. Some of these feeder roads have speed limits of 40-50MPH. Dangerous. Look up the road on google maps. Landover road largo Maryland, do a street view and tell me what you think. Would you ride there at 530 am in the dark? With cars going by you at 50MPH? I know the bicycle has the right to do so, as I have the right to climb a mountain in the middle of the winter. Just because you are allowed to does not mean it is the smartest decision.
It is quite sad. This area has so many people yet the roads here are stacked against bikes. That coupled with the residents attitudes equals some pretty dangerous biking conditions. I wish it was different. I used to love riding my bike around town.