Esteban Santiago-Ruiz is believed to be the gunman in the Fort Lauderdale airport shooting, which left at least five people dead and eight wounded on Friday. Early indications point to a man with psychiatric problems. There does not appear to be any known connections to terrorist groups.

Santiago-Ruiz was in federal custody, the Broward County Sheriff Scott Israel said. He will be federally charged, the FBI said Friday night.

Santiago-Ruiz’s brother told the Associated Press that he had been receiving psychological treatment recently. Bryan Santiago said that he didn’t know what his brother was being treated for and that they never talked about it over the telephone.

The FBI confirmed that in Nov. 2016, Santiago-Ruiz walked into an FBI office in Anchorage and claimed his mind was being controlled by a U.S. intelligence agency and that he was being forced to watch videos for ISIS. He was sent to a psychiatric hospital after police were called, sources said.

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Law enforcement officials told CBS News’ Jeff Pegues that Santiago-Ruiz was traveling from Alaska to Fort Lauderdale, and got in an argument on one leg of the trip. CBS News’ Pat Milton reports that the suspect was flying the red-eye flight out of Anchorage on Delta and landed in Minneapolis Friday morning. He then connected to a flight to Fort Lauderdale.

Within a few hours of the shooting, details remained murky about the suspected shooter, and his motive was still under investigation. Law enforcement sources said there appeared to be no link to terrorism.

FBI sources told CBS News’ Pat Milton that they ran a full database check on Santiago-Ruiz, and they found no connection to terror groups. The fight is under investigation.

Santiago-Ruiz had active-duty military identification on him at the time of the shooting. It was unclear if the identification was the gunman’s, Sen. Bill Nelson said on Friday.

Santiago-Ruiz served in the Alaska National Guard, a spokesperson confirmed to CBS News. He received a general discharge for unsatisfactory performance in August 2016. According to the Alaska Army National Guard, Santiago-Ruiz joined the Puerto Rico National Guard in December 2007, and served with that unit in Iraq from April 2010 to February 2011. He was in the Army National Reserves before joining the Alaska National Guard in 2014, they said.

The Pentagon told the Associated Press that Santiago had gone AWOL several times during his stint with the Alaska National Guard and was demoted - from specialist to private first class - and given a general discharge, which is lower than an honorable discharge.

He was also investigated as part of a child porn investigation in either 2011 or 2012, law enforcement sources told CBS News. Three weapons and a computer were seized, but no charges were filed, sources said.

Santiago-Ruiz’s aunt, Maria Ruiz, told the New Jersey Bergen-Record that he was happy after the recent birth of his son, but he had “lost his mind in Iraq.”

“I don’t know why this happened,” she said.

Bryan Santiago told the Associated Press that his brother was born in New Jersey but moved to Puerto Rico when he was 2. A spokesperson with the Anchorage Police Department has confirmed the suspect arrested in connection with the shooting is an Anchorage resident, CBS affiliate KTVA reports.

The FBI is investigating some of his life in Alaska, the FBI said a press conferece Friday night.

There was heavy law enforcement presence in Anchorage near a house where Santiago-Ruiz was believed to have lived, CBS affiliate KTVA reports. Neighbor Perette Carter, whose lived there for 30 years, said Santiago-Ruiz lived nearby for two years and was “pleasant.” A mailbox at the home also listed him as a resident.

“I just thank God that he didn’t shoot anybody down here and I just feel bad for the people in Florida, that what he did, but you know, he’s captured and that’s a good thing,” Carter told KTVA.

FBI agents late Friday were investigating at a house in Union City, New Jersey, where a relative of Santiago-Ruiz’s lives, CBS New York reports. The FBI confirmed that that there was an active investigation at the home Friday evening. About eight federal agents were seen coming and going through the front door, before leaving the scene in unmarked cars with emergency lights.