None of this adds up. The "white pellets" really really sound like perlite and it would be great to see a picture.
The bigger issue is your statement that some of the "top buds" were clipped. Are you sure this was done by a human?
If you really think anyone is messing with your plants you should take them now. No one is spending time tending a crop that they won't harvest.
No pictures and a very odd story... Not sure if I buy all this...