Who ordered the assassination of John Lennon

As john Lennon entred the old spooky Dakota building on December 8th 1980 ThenMark Chapman  dropped into a military stance - legs spread for maximum balance, two hands gripping his gun, a .38 revolver, took aim, shot and killed john Lennon. 
The only problem  being that 8 bullets were picked up, not bad coming from a gun that could only shoot 5!
The redundent  lone nut theory, inacurate eye witness acounts (only about 4 from 30 were ever called to give testimony) and much more prove the conspiracy of silence surrounding John Lennons murder.