Will we ever get to the bottom of what happened last week in Libya, when U.S. Ambassador Chris Stevens and three other Americans were killed? Perhaps. But the clues are slow to develop.

FOX News Radio's Courtney Kealy, who reported extensively from Libya during the uprising has Part Four of our series, "Death of an Ambassador":

Securing America.

White House spokesman Jay Carney saying at this point in the investigation in Benghazi, there is still no evidence it was a pre-planned attack.  But retired Col. David Hunt, who has assisted the FBI on these kinds of investigations, says the crime scene has likely been contaminated already beyond recognition.

(Hunt) "It's going to be very difficult, and the cooperation level that the Libyans are going to have to give is unprecedented.  So I think that the FBI's role in this, although it sounds good to say FBI is investigating, is going to be very limited."

While the FBI has good forensic capabilities, it's going to be tough to gather evidence.

Courtney Kealy, FOX News Radio.

Click HERE for more of the series "Death of an Ambassador"

Click HERE to read Courtney Kealy's American Dispatch on Ambassador Stevens' death

Follow Courtney on Twitter: @CourtneyKealy