Updated

The FBI was not advised in advance that Ali Ani al-Harzi, a leading suspect in the U.S. consulate attack in Benghazi, Libya, was being released by the Tunisian court, an investigative source familiar with the case tells Fox News.

While FBI officials in Washington did not deny the report, a spokesman declined to comment.

Fox News separately was told that FBI agents got useful information from al-Harzi during a two-hour interrogation of the Tunisian national last month, but there was not enough to rule him in or out of the Benghazi attack.

Ansar al-Sharia Tunisia, an extremist group with ties to Al Qaeda, released on its Facebook page a video purporting to show al-Harzi as he walked free Jan. 7 after Tunisian authorities cited a lack of evidence.

“A lot of these groups are emboldened after Benghazi and after a series of basically missteps by the American government trying to investigate what happened in Benghazi,”  Tom Joscelyn, with the Foundation for Defense of Democracies, was first to write about the al-Harzi tape for the Long War Journal.

“We're still compiling the evidence on how these groups are interlinked," Joscelyn said. "But here you have with al-Harzi, you have an individual who was involved in the attack on the U.S. consulate in Benghazi. We know that members of Ansar al Sharia in Benghazi were involved in that same attack and now we know that Ansar al-Sharia Tunisia has been celebrating and really urging for the release of al-Harzi in Tunis. Therefore you're seeing this common interest in what happened in Benghazi and the individuals responsible.”

Al-Harzi was detained by Turkish authorities in October after he was linked to the consulate attack through social media postings. He then was transferred to Tunisian custody, where FBI access was blocked until Republican Sen. Lindsey Graham intervened.

“I can only imagine what would have happened if the president of the United States would had picked up the phone and called the prime minister to say this is a priority for the country,” Graham told Fox News last week.

This is the third time Ansar al-Sharia in Tunisia has used social media to write about the Benghazi suspect. After al-Harzi was interviewed, Ansar al-Sharia posted pictures, purportedly showing the three FBI agents involved.

“It was meant to be provocative and it was meant to show that the FBI cannot operate with total impunity in Tunis and elsewhere,” Joscelyn said.

While a second suspect, Muhamed Jamal Abu Ahmed, was detained by Egyptian authorities in early December, the head of the House Intelligence Committee -- who is regularly briefed on the case -- says hard-working FBI agents are not getting enough support for their investigation.

“It’s just not going well. It's slow,”  Republican Rep. Mike Rogers said. “We're not getting great cooperation from governments that should be cooperating ... and it doesn't seem its getting the resources and attention the administration should give to it to actually get to the bottom of this.”

The White House did not immediately respond to a request for comment Wednesday evening.