Where is Moorehead's safe?

Hint 1 of 6:

It's hidden pretty well, but it is in his office.

Hint 2 of 6:

Move everything you possibly can and it should turn up.

Hint 3 of 6:

Start out by moving the chair.

Hint 4 of 6:

Then, you need to move the shelf of books in the far-right corner of the
bookcase.  That's where you'll find the safe.

Hint 5 of 6:

Only Moorehead and Gardner have the combination.

Hint 6 of 6:

Do you think Gardner might have carried it with him?