As it's worked out, both of McVeigh's sisters, Jennifer and Patty, are still alive. I suspect that was at least a part of the deal. And if anything ever happens to them, a suicide, hit-and-run accident, a plane crash or a death during the commission of a robbery, just as examples of things that have happened that have happened to other OKC witnesses, then don't be too surprised at a release of additional information on Mc Veigh and who he thought he was working for- Andy Strassmeier was reportedly escorted out of the US across the Mexican border by federal agents two days after the bombing, and had been followed and reported entering a BATF office through an *Employees Only* entrance that required ID passcard access.
But the anniversary of McVeigh's execution is also coming up on 11 June. Perhaps we'll see a bit more by then.