The contractor and the assassin

Oh, the demise of the empire!
Receded and dark its walls began to fall

The alliance, no one saw it die
The scene of the crime was not checked for evidence
Now it is all gone

The theory seems all too easy
You see, the thesis is said to be dead and so are you

Name the contractor and the assassin
Memorize the face and the plates and the prayer

Throw your oars overboard