The gun believed to have been used by the Fort Lauderdale, Florida, airport shooter to kill five people and wound six more is the same weapon that was once taken away from him because of his mental state, sources told NBC News on Sunday. 
 
 Former Army reservist Esteban Santiago, 26, walked into an Alaska FBI office with his infant child on Nov. 7 "to report that his mind was being controlled by a U.S. intelligence agency," Special Agent in Charge Marlin Ritzman told reporters Saturday. 
 
 Agents then called Anchorage police, who retrieved a gun from his car outside. 
 
 "Santiago was having terroristic thoughts and believed he was being influenced by ISIS," Anchorage Police Chief Chris Tolley said in a news conference Saturday. 
 
 Esteban Ruiz Santiago, 26, in a police booking photo. Broward County Sheriff's Office / AP 
 
 The FBI confirmed that Santiago's child was taken into the "constant custody and care of the FBI" until Santiago's girlfriend, the child's mother, could pick him up. 
 
 His brother Bryan Santiago told NBC News partner Telemundo in Puerto Rico that Esteban was taken by police to a mental health evaluation but was released after only four days. 
 
 Police returned the handgun to him one month later, officials said. 
 
 On Sunday, federal law enforcement sources told NBC News that they believe that the gun authorities seized was the same weapon he allegedly used in Friday's shootings, a Walther 9mm pistol. 
 
 Ritzman said it's normal for people to deliver walk-in complaints at FBI offices across the country. He added that nothing in Santiago's actions or history indicated a need to do anything more than to take him to the mental health facility. 

 FILE- In this Jan. 7, 2017 file photo, George Piro, special agent in charge of the FBI's Miami Division speaks during a news conference at Fort Lauderdale-Hollywood International Airport Terminal, in... (Associated Press) 
 
 FILE- In this Jan. 7, 2017 file photo, George Piro, special agent in charge of the FBI's Miami Division speaks during a news conference at Fort Lauderdale-Hollywood International Airport Terminal, in... (Associated Press) 
 
 FORT LAUDERDALE, Fla. (AP) — The FBI agent who interrogated Saddam Hussein alone for months after the former Iraqi leader's capture is now leading the investigation into the Florida airport shooting rampage blamed on an Iraq war veteran. 
 
 George Piro, special agent in charge of the FBI's Miami field office, was Saddam's sole interrogator beginning in January 2004. In previous interviews, Piro has said Saddam did not know his true identity — the Iraqi leader called him "Mr. George" — and that he posed as a high-level envoy who answered directly to then-President George W. Bush. 
 
 Now the 49-year-old Piro, a native of Beirut, Lebanon, fluent in Arabic and Assyrian, is in charge of the FBI investigation into the shooting at Fort Lauderdale-Hollywood International Airport that left five people dead and six wounded. Federal prosecutors have charged Esteban Santiago, 26, with airport violence and firearms offenses that could bring the death penalty if he is convicted. 
 
 In announcing the charges filed Saturday, Piro said his thoughts are with the victims and their families. 
 
 "I want to ensure these families that law enforcement is working tirelessly in order to ensure justice is served," he said. 
 
 Piro, an FBI agent since 1999, moved with his family from Lebanon to California's San Joaquin Valley as a teenager. After high school he enlisted in the Air Force, then became a police officer for a decade in Ceres, California, followed by a job as an investigator in the local prosecutor's office. 
 
 Once he joined the FBI in Phoenix, Piro was one of only a handful of Arabic-speaking agents — a group that suddenly was in great demand after the Sept. 11, 2001 terror attacks and the subsequent U.S. invasions of Afghanistan and Iraq. In 2003, Piro was promoted to the FBI's Counterterrorism Division at headquarters in Washington, leading to his work as Saddam's interrogator. 
 
 In later interviews, including a 2008 appearance on CBS's "60 Minutes" program, Piro said he met daily with Saddam in a windowless room and worked to gain his trust by becoming his only provider of necessities and such things as paper for Saddam to write poetry. 
 
 Eventually, Piro said Saddam confirmed that Iraq did not have weapons of mass destruction prior to the U.S. invasion but might seek them in future to deter Iran and other threats. Saddam also denied any links to al-Qaida and Osama bin Laden, Piro has said. 
 
 Saddam also liked to brag about how he escaped U.S. airstrikes and capture, according to Piro. 
 
 "What he wanted to really illustrate is . . . how he was able to outsmart us," Piro told "60 Minutes." ''He got rid of his normal vehicles. He got rid of the protective detail that he traveled with, really just to change his signature." 
 
 Saddam was later tried and executed by hanging in December 2006. 
 
 Santiago, the airport shooting suspect, also served in Iraq in 2010 with the Puerto Rico National Guard as part of an engineering battalion, guard officials said. Santiago later served in the Army Reserves and Alaska National Guard. 
 
 After Iraq, Piro moved on to top FBI counterterrorism jobs in Washington, including a White House position involving high-value detainee interrogation that works with various intelligence agencies. 
 
 Since taking the top Miami FBI job, Piro has overseen work in more domestic areas such as health care fraud, identity theft and tax fraud, Ponzi schemes and mortgage fraud — all areas where South Florida is among the nation's leaders. Bank robberies, violent street gangs, public corruption and smuggling of humans and drugs round out much of the work for the Miami office's roughly 1,000 agents and employees. 
 
 Since Friday's shooting, Piro has been careful to say no evidence linking Santiago to terrorism has been found but such connections have also not been ruled out. 
 
 "It's way too early in the investigation. We're looking over all of his social media, things like that. It's giving us a picture of the individual, but it's way too early for us to rule out anything," Piro said Saturday. "We're pursuing all angles on what prompted him to carry out this horrific attack." 
 
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 Follow Curt Anderson on Twitter: http://twitter.com/miamicurt
– The FBI agent who interrogated Saddam Hussein alone for months after the former Iraqi leader's capture is now leading the investigation into the Florida airport shooting rampage blamed on an Iraq war veteran. George Piro, special agent in charge of the FBI's Miami field office, was Saddam's sole interrogator beginning in January 2004. In previous interviews, Piro has said Saddam did not know his true identity and that he posed as a high-level envoy who answered directly to George W. Bush. Piro said he met daily with Saddam in a windowless room and worked to gain his trust by becoming his only provider of necessities and such things as paper for Saddam to write poetry, the AP reports. Piro said Saddam eventually confirmed that Iraq did not have weapons of mass destruction prior to the US invasion, but that he might seek them in the future to deter Iran and other threats. Now Piro's in charge of the FBI investigation into the shooting at Fort Lauderdale-Hollywood International Airport that left five people dead and six wounded. Federal prosecutors have charged Esteban Santiago, 26, with airport violence and firearms offenses that could bring the death penalty if he's convicted. NBC News reports the gun Santiago is believed to have used in Friday's shooting was taken away from him on Nov. 7 after he went to an Alaska FBI office to report a US intelligence agency was controlling his mind. Anchorage police removed the weapon from his car, and he was permitted to pick it up from them a month later.