Jeremy Werner spoke to Lawson and there are some interesting tidbits (free article):
http://www.scout.com/college/illinois/story/1735346-dwayne-lawson-i-have-a-lot-to-prove
It sounds like the transfer has been in the works for a year, but he had to go to juco to address academic issues. (If this is the case, though, why couldn't he get it sorted out quicker and be coming here for the summer? Sounds like he still has work to do in the classroom.)
It also sounds like the drug test issue was due to taking Adderall for ADHD. I'd normally be super skeptical, but honestly the story he gave Werner doesn't sound like the kind of thing a 20 year-old would make up.
Overall, I'm cautiously optimistic. He sounds like a good kid who just needs to get his **** together, like some other 20 year olds I know.