The thing that seems to be the weakest link in it being an inside, detonation, job, is, that there would be dozens and dozens of people involved, and it seems that at least one of those involved would have told someone either purposefully, or accidentally, by now, and it would have made some news somewhere. Certainly, over a 20 year span of time, someone involved would have had regrets about being involved with such a despicable act.
The thing that seems to be the weakest link in it being an inside, detonation, job, is, that there would be dozens and dozens of people involved, and it seems that at least one of those involved would have told someone either purposefully, or accidentally, by now, and it would have made some news somewhere. Certainly, over a 20 year span of time, someone involved would have had regrets about being involved with such a despicable act.
It wouldn't require dozens of people though. Just one person could have done it without being noticed.