Break in bed of tacoma 2010

My Tacoma was broken in last night. I have a Century tonneau cover which I always lock. They got to open the tailgate and stole stuff from the bed. If they were able to open the cover they would steal everything. Do you think locking the tailgate would prevent this? or they would do it anyway?
... I just realized there is no locking mechanism on my tail gate!

 

Depends on how good they are and what your stúff is worth to them .

Doest that cover covèr the top of the tailgate? ( I had a Leer once). If so and locked, how was the gate opened?

And when opened, why couldn't they have taken everything in the bed anyway?

 

The cover was locked, if you look closely in the pics, maybe u can see the tempered with the tailgate on the right side, there is a dent on the top right corner. The tailgate on the right side was disengaged when I saw it. I had to put it back in place. I'm thinking about possibility of any lock for the tail gate, and if that will prevent the fuckers.

 

Pop n Lock sells a locking tailgate handle