Indeed "they" may have good reason to keep the truth deeply buried.

"The Iraqis have a great deal of what they do deeply buried."

There might be some serious dangers here, in giving you access to such deeply buried activities.

The knowledge was there, deeply buried, lost but not forgotten.

Or, if I did, the knowledge was deeply buried in my mind.

Over the years, she became deeply buried under the sand by wave action.

Then, suddenly comprehension came to him from some deeply buried place, and it showed on his face.

It was not anger, so much as a deeply buried resentment.

Still more seemed to remind her of things deeply buried.

Now the doubts of the previous day were deeply buried.