The study is still ongoing and new evidence comes up every once in a while. A map was recently found that had some interesting hints, though the property isn't able to be excavated yet. The general belief is that some failure of the colony due to disease, hunger, etc caused the survivors to disperse into the local native population. The Lost Colony project is trying to track down DNA in the modern population in hopes of proving that theory.

I don't really specialize in Roanoke - but thanks to my work in Atlantic World history, I've interacted with and talked with people who are. I've also had to work for the Lost Colony project briefly. I never looked into the primary sources of Jamestown, but apparently there are documents there that talk about how in 1607 that some survivors of Roanoke went and became part of North Carolina - Virginia tribes and that they were killed to prevent them from helping the new colonists in Jamestown. Now, the validity of these reports from the colonists have and should be questioned. I wish I could find the primary source that has this account, but I can't seem to find it. Let's just say that it's a lead to a explanation - and since other leads have even less evidence, a number of historians feel obliged to go with that explanation.