The nightmare Sean Smith’s family faced following his death in Benghazi got worse when they learned the Sept. 11, 2012 attack was planned by a jihadist who had been in U.S. custody only a few years earlier.

Smith, a State Department information specialist, was one of four Americans killed when Al Qaeda-linked terrorists assaulted U.S. consular and CIA facilities in the Libyan city. But the knowledge that Abu Sufain bin Qumu helped plan the attack after being released from the Guantanamo Bay military prison has left his family wondering if his death could have been avoided – and asking why the Obama administration is so intent on releasing more detainees.

“Turning loose all these prisoners doesn’t make any sense,” Sean’s mother Pat Smith told FoxNews.com. “Give me the keys so I can keep them locked up.

"It was a slap in the face of our family...and it’s a slap in the face of America."

- Michael Ingmire

“I don’t trust them [the presidential administration] anymore. How is turning them loose keeping us safe? How did that benefit my son?”

Bin Qumu was released from Guantanamo Bay in 2007 under a new program started by then-President Bush, and repatriated to his home country of Libya. Once there, he rose to the leadership ranks of the militant Islamist group Ansar al-Sharia, the group behind the Benghazi attacks.

“It’s absolutely dangerous to America to release these guys,” Smith’s uncle, Michael Ingmire, told FoxNews.com. “It was a slap in the face of our family,” he said of bin Qumu’s release. “And it’s a slap in the face of America.

Several other Guantanamo alumni have ended up back in the war against the west, with many re-entering U.S. radar only after they were killed.

Airat Vakhitov and Rustam Akhmyarov were released from Gitmo in 2004. They were arrested nearly a year later by authorities in Moscow for allegedly preparing a series of attacks in Russia. Vakhitov, a Tajikistan national, was accused of using a local human rights group as cover for his activities.

Said Mohammad Alim Shah was repatriated to Afghanistan in March 2004. After his release, he was responsible for kidnapping two Chinese engineers, took credit for a hotel bombing in Islamabad and orchestrated a 2007 suicide attack which left 21 people dead.

Abdullah Ghoffor went back to Afghanistan at the same time and became a high-ranking Taliban commander who planned attacks against U.S. and Afghan forces before being killed in a raid.

Abdallah Salih al-Ajmi, former detainee from Kuwait, committed a successful suicide attack in Mosul, Iraq, in March 2008. That came three years after he had been freed from Guantanamo and transferred to Kuwait, where a court acquitted him of terrorism charges.

Earlier this month, a video released by a group called the Guardians of Shariah featured former Guantanamo detainee Ibrahim al Qosi, now a religious figurehead and in a key position of leadership in Al Qaeda of the Arabian Peninsula (AQAP). Al Qosi, who among many roles was the cook and chauffeur for Usama bin Laden, was imprisoned in Guantanamo in 2002 and released 10 years later.

President Obama has made it a key policy objective to free Guantanamo Bay detainees or transfer them to U.S. prisons or foreign countries. One of the main reasons cited is that Guantanamo Bay, the facility that has long housed the worst of the worst, is infamous among terrorist groups and helps drive anger at America.

It also has sparked outrage from the international community since its inception and has often been referred to as a modern-day gulag.

"[T]his notion of a gross injustice, that America is not living up to its professed ideals," he said at his final press conference of the year last Friday. "We see the Internet traffic. We see how Guantanamo has been used to create this mythology that America is at war with Islam."

The release of prisoners at Guantanamo first started during the presidency of George W. Bush in 2005 when nearly 200 detainees were released before any tribunals were held.

With 107 prisoners remaining in the facility that held more than 600 at peak capacity, 17 are now slated to be freed or transferred to the custody of other nations. A key to advancing the plan to finish emptying out Guantanamo is demonstrating that most detainees are peaceful once freed.

According to a March 2015 memo released by the Office of the Director of National Intelligence, of the 647 detainees transferred or released, 17.9 percent were confirmed of reengaging in extremist activity with another 10.7 percent suspected of doing the same.

But the relatively low percentage of detainees returning to terrorism once freed misses a key point, say experts. Gitmo veterans enjoy a special status among jihadists that goes beyond the battlefield.

“Current arguments over terrorist recidivism upon release from Gitmo focus vary based on what it means to ‘rejoin’ the terrorist cause,” said Ryan Mauro, a national security analyst at the Clarion Project, a nonprofit think tank that monitors the threat of international terrorism. “The rate is lower if you only consider those who went back to physical fighting and it is higher if you include those who rejoined terrorist groups. But we often miss another factor: What about those who use their rock star status to radicalize without engaging in violence? We must remember this is an ideological war.”

Mauro doesn’t oppose closing Guantanamo Bay, but so far has not heard a viable alternative plan for locking up dangerous terrorists caught waging war on America. And he rejects the idea that holding prisoners there is a recruiting tool for ISIS or Al Qaeda.

“Closing Guantanamo Bay will have no impact on terrorist recruitment and radicalization,” Mauro said. “There is not a single case that I am aware of where a moderate, peace-loving Muslim became angry over the Gitmo issue and suddenly decided to wage violent jihad, behead innocent people, implement theocracy and commit human rights abuses like executing gays and abusing women.”

No one should be surprised when a committed terrorist proves not to have been rehabilitated by a lengthy stay at Guantanamo, said Ingmire, who is against turning loose any suspects who have not been found innocent.

“[The] administration treats these prisoners like they would drug lords as opposed as terrorists,” he said. “It’s absolutely irresponsible. Releasing a suspected terrorist before they are properly tried is, to me, aiding and abetting the enemy.”

Perry Chiaramonte is a reporter for FoxNews.com. Follow him on Twitter at @perrych