Ambassador Stevens was set up to die because his stories of gun-running, child trafficking and drug-running on behalf of the CIA in order to promote regime change in Libya using terrorists funded by these illegal activities, were leaking out and it was only a few months until the election. Subsequently, Ambassador Stevens had to be silenced. And Petraeus had to be put in a place where he was not forced to testify before Congress because he could not take the 5th before Congress.
At the same time, Clinton was broadcasting Stevens whereabouts and she refused to provide the extra protection Stevens was so desperately requesting. Being that Stevens was working for the CIA, then head of the CIA, David Petraeus, would have known about Chris Stevens activities. To protect Obama’s 2012 election, both Stevens and Petraeus had to be gone.