The CIA's investigation into the deadly suicide attack on a base in Afghanistan concluded that "shortcomings across several agency components" caused a security failure, as agents mistakenly welcomed the attacker as a trusted informant, according to a memo about the long-awaited internal report.

The report also notes that some within the CIA were suspicious of the informant three weeks or so before the suicide attack, based on concern that he was still a hardened terrorist, an intelligence official told Fox News, but these suspicions were balanced against the confirmed intelligence the informant had provided.

CIA Director Leon Panetta, in an e-mail Tuesday afternoon to agency personnel obtained by Fox News, said there was no single point of failure last December at Khost, Afghanistan, where the bomber killed seven for the worst loss of life in the agency’s history.

“In this case, the task force determined that the Khowst assailant was not fully vetted and that sufficient security precautions were not taken," Panetta said. "These missteps occurred because of shortcomings across several Agency components in areas including communications, documentation and management oversight. Coupled with a powerful drive to disrupt al-Qa’ida, these factors contributed to the tragedy at Khowst.”

Panetta said the war against Islamic extremism was becoming increasingly dangerous, adding “while we cannot eliminate all of the risk involved in fighting a war, we can and will do a better job of protecting our officers.”

Click here for a PDF of the memo.

On Dec. 30, a Jordanian double agent who claimed to have knowledge of the Al Qaeda senior leadership set off a suicide device at Forward Operating Base Chapman in Khost.

Fox News has learned that the investigation into the attack yielded 23 recommendations -- among them, a newly created counter-intelligence unit that will specifically assess the high-risk,high-gain operations like Khost. Also, there will be a new position in the agency’s CTC, or counterterrorism center, that will enhance coordination on high-risk operations between various departments.

The families of the agents killed at Khost were told Tuesday the report was complete. They have the option of a personal briefing at CIA headquarters over the coming weeks.

Significantly, a senior former intelligence official says the CIA director will not opt for accountability boards, which would examine the individual’s actions at Khost and whether a specific person or persons were to blame. The former official tells Fox News there is no desire to place blame on the dead, and the agency’s intent it to take the lessons learned to avoid a similar tragedy in the future.

Fox News also has learned that the Jordanian intelligence service is not specifically blamed for the bombing because officials understand that the U.S. and partner intelligence services must “succeed together and face setbacks together.”

A plaque was placed by Panetta at the Khost site on his recent trip to the region. The verse on the plaque is from Isaiah – it was meant to capture the ideal of putting service before self: "And I heard the voice of the Lord , saying, 'Whom shall I send, and who will go for us? Then said I, Here am I, send me.'"

Catherine Herridge is an award-winning Chief Intelligence correspondent for FOX News Channel (FNC) based in Washington, D.C. She covers intelligence, the Justice Department and the Department of Homeland Security. Herridge joined FNC in 1996 as a London-based correspondent.