I still think it's more than just coincidence that there was going to be an Ecstasy Party the night of March 16. If you check a few of her close friend's Twitter feeds, you can find more information. (I understand drugs/alcohol are common at this age, but the timing makes me think twice.)
I hope that her friends aren't withholding information because they are scared---the $10,000 reward to "the first person" with information seems like it might be to entice one of these kids to come forward.
If Ecstasy had anything to do with this, the perp is probably someone that she knows directly or through a friend (a dealer's friend perhaps?). Her friends could easily divulge who her/their dealers are...but will they risk that for $10,000?
On another note...
On March 15th, between 2:00-3:00pm, Sierra was tweeting about someone deserving to be punched, something making her feel really bad, and something happening "one year ago"
What happened 1 year ago? Was it to the day?
#findsierra
JMO