They know darn well who did the deed. It was the boss, thus the cover-up.
Also, this is what happens when you hire based on things other than experience and aptitude. So many violations of common sense.
It’s not hard to figure out who did it. I used to run Big Brother on our systems. One of the functions I wrote did a who every 5 minutes so I knew who was logged on and when.
We had an incident where some files went missing. A month after they asked me find out who did it. I found out who was logged on at the time the files went missing and went to his .sh file and found the rm command. Busted. I felt bad that I had to narc on a nice guy who meant well by freeing space.