This appears to be the case.
CNN reports that there were allegedly “dozens” of CIA operatives on the ground during the Benghazi attack and the agency is doing its utmost to conceal its involvement.
CNN’s sources say that, since January, some operatives that were involved in the agency’s mission in Libya are being polygraphed monthly to determine who, if anyone, is talking to Congress or the media. Sources describe the efforts as pure intimidation, and say there are threats to end the careers of unauthorized leakers.
This makes Benghazi an ever bigger scandal than we thought, with a government agency actively undermining legitimate congressional oversight in order to cover up either real crimes or its own incompetence.
It also suggests that the CIA was carrying out one (or possibly both) of the secret (and possibly illegal) operations that been widely rumored to be the real reason behind the Benghazi coverup:
They were already running arms (including surface-to-air missiles) to Syrian rebel, well in advance of Obama’s public declaration, or
Benghazi was an extrajudicial center for “harsh interrogation methods” of the sort Obama theoretically banned, as suggested by former CIA Director David Petraeus’ former mistress Paula Broadwell.
Either way, Obama lied, and Americans died to cover up Obama’s lies, and now even more people are being forced to lie, or at least refrain from talking to investigators seeking the truth, in order to cover up the coverup.