Mohammed Saeed al-Shamrani, 21, killed three and wounded 12 others in the attack before he was shot dead by police. This picture was released by the FBI on Saturday evening

The Saudi gunman who killed three people at a naval base in Pensacola and wounded eight others visited the September 11 memorial in New York City just days before the shooting.

Senior law enforcement officials also say that the killer, Second Lt. Mohammed Saeed al-Shamrani, 21, made preparations for the shooting by filing paperwork to purchase a gun in April.

The revelations about his movements are part of efforts by investigators to establish an exact timeline in the weeks leading up to Friday’s shooting rampage, according to The Daily Beast.

Investigators are said to have questioned at least five other Saudi airmen who were with al-Shamrani during his four-day trip to New York City and are also in the United States as part of a military training program.

None of those Saudis appear to have had any involvement in the shooting, law enforcement officials told The Daily Beast.

The Saudis also told investigators that they noticed nothing unusual about al-Shamrani’s behavior during his trip to New York from November 28 until December 1.

The Saudis visited New York’s most popular tourist destinations, including the Statue of Liberty, Central Park, the Christmas tree at Rockefeller Center, and the 9/11 museum, according to investigators. They stayed at a lower-end hotel in midtown Manhattan.

‘All the places they went were all the places tourists go see what this country’s all about,’ one investigator told The Daily Beast.

Investigators learned that a few days before the shooting, al-Shamrani and at least five other Saudi airmen traveled to New York City, where they visited tourist sites including the 9/11 memorial (above)

Investigators noted that the 9/11 museum has pictures on display of the hijackers - 15 of whom were Saudi nationals.

Three days after returning home to Florida, al-Shamrani hosted a dinner party for his fellow Saudis.

It was during that event that he screened a disturbing video showing a montage of mass shootings.

After the shooting, a number of the Saudi airmen took cell phone video near the scene.

It emerged as:

Investigators face mounting pressure Monday to deliver answers on the motive

A cyber attack crippled the city of Pensacola over the weekend and officials do 'not yet don't know' if two incidents are 'connected or not'

Key part of the investigation into the shooting now turns to Texas, ABC reports

FBI confirmed Sunday al-Sshamrani had legally purchased the Glock 9mm pistol

Authorities also believe he authored a series of social media posts in which he talked about U.S. support for Israel and scolded Americans for being anti-Muslim

His fellow Saudi students are speaking directly with American investigators

Colleagues say he appeared more religious after a trip home in February

Family members and others identified the three dead as Airman Apprentice Cameron Scott Walters, 21, of Richmond Hill, Georgia (left); Airman Mohammed Sameh Haitham, 19, of St. Petersburg, Florida (center); and Joshua Kaleb Watson, a 23-year-old graduate of the U.S. Naval Academy (right)=

Al-Shamrani also filed a complaint against an instructor at the training center who called him ‘porn stash’ in front of about 10 other aviation students earlier this year.

‘I was infuriated as to why he would say that in front of the class,’ al-Shamrani wrote in his April complaint, according to The New York Times.

The FBI declined to comment on the incident. Investigators do not believe that the incident had any connection to Friday’s shooting, the Times reported.

As of Sunday, investigators have no indication that al-Shamrani was helped by others.

On Monday the mayor of Pensacola revealed the city had been hit by cyber attack just hours after the shooting.

Mayor Grover Robinson admitted Monday that officials do 'not yet don't know' if two incidents are 'connected or not'. The issue is thought to be ongoing.

'We have discussed and we have talked with the FBI. It's my understanding (the city) sent stuff to them, and we're continuing to work. Our computer people worked through the weekend to see what was happening', Robinson added.

Investigators combed through the cell phone footage from his New York trip and found nothing unusual that would arouse their suspicions, according to The Daily Beast.

‘Nothing before the fact, nothing during,’ one law enforcement official said.

Meanwhile, new information has been gleaned about the long process that al-Shamrani went through to legally obtain the 9mm Glock 45 semiautomatic pistol used in the shooting.

Law enforcement officials said that the group of Saudis which included al-Shamrani also visited popular tourist sites like the Christmas tree at Rockefeller Center (left) and the Statue of Liberty (right)

The Daily Beast learned that al-Shamrani obtained a Florida hunting license that allowed him to take advantage of a loophole in federal law banning foreign nationals from buying a gun.

The loophole allows foreigners with a valid visa to buy a gun if ‘in possession of a hunting license or permit lawfully issued in the United States.’

One investigator said al-Shamrani’s choice of a Glock 45 with an extended magazine meant that the only thing he intended to hunt was ‘people.’

Members of the Air Force Old Guard Carry team carry the transfer case of Ensign Joshua Caleb Watson at Dover Air Force Base in Dover, Delaware, on Sunday

Members of the Air Force Old Guard Carry team carry the transfer case of Seaman Apprentice Cameron S. Walters at Dover Air Force Base on Sunday

Members of the Air Force Old Guard Carry team carry the transfer case of Seaman Mohammed Haitham on Sunday. Acting Navy Secretary Thomas Modly (center) and Navy Admiral Michael Gilday (right), the chief of naval operations, look on

According to The Daily Beast, the gun shop in Pensacola which sold the weapon to al-Shamrani checked with authorities to confirm the validity of his visa.

The Saudi national was issued the visa in Riyadh. He arrived for military training in the US in August 2017.

In late July, al-Shamrani completed the 15-week process to buy the gun despite the fact that he was not allowed to carry the weapon onto the premises of the Naval Air Station in Pensacola.

By law, al-Shamrani also would not have been able to board an airplane with the weapon if he were to fly back to his native Saudi Arabia.

ALSHAMRANI'S DISTURBING TWITTER ACCOUNT AND HIS PRE-SHOOTING 'MANIFESTO' The now-deactivated Twitter account purportedly belonging to Alshamrani included: - A variety of anti-Israel postings and a quote from deceased al-Qaeda leader Osama bin Laden - A lengthy manifesto posted at 4:39am Friday, less than two hours the shooting. The manifesto read in part: 'I'm against evil, and America as a whole has turned into a nation of evil. 'I'm not against you for just being American, I don't hate you because [of] your freedoms, I hate you because every day you [are] supporting, funding and committing crimes not only against Muslims, but also humanity.... Advertisement

Investigators are now trying to figure out if al-Shamrani acted alone or if he was recruited and groomed as a sort of ‘sleeper agent.’

If al-Shamrani was intent on killing Americans, investigators want to know why he bought a gun instead of waiting to come into possession of a far more powerful weapon that could maximize casualties, like a fighter jet armed with missiles or bombs.

‘Get him up in an F-15 and crash it into a building or drop a bomb,’ one law enforcement official said.

A US official said on Sunday that al-Shamrani had apparently gone on Twitter shortly before the shooting to blast US support of Israel and accuse America of being anti-Muslim.

The revelation was made as the FBI confirmed it is operating on the assumption the attack was an act of terrorism.

The Royal Saudi Air Force airman, who was killed by a sheriff's deputy during the rampage at a classroom building Friday, was undergoing flight training at Pensacola, where members of foreign militaries routinely receive instruction.

'We are, as we do in most active-shooter investigations, work with the presumption that this was an act of terrorism,' said Rachel J. Rojas, the special agent in charge of the FBI's office in Jacksonville.

Authorities believe the gunman made social media posts criticizing the US under a user handle similar to his name, but federal law enforcement officials are investigating whether he authored the words or just posted them, said the official, who was not authorized to discuss the matter publicly and spoke to The Associated Press on condition of anonymity.

The FBI Evidence Response Team is pictured continuing their methodical search for clues at the base on Saturday. FBI terrorism investigators have been also been investigating, according to reports

Naval Air Station Pensacola will remain closed until further notice, officials said Saturday. The building where the shooting took place is pictured

All foreign students at the Pensacola base have been accounted for, no arrests have been made, and the community is under no immediate threat, Rojas said at a news conference.

A Saudi commanding officer has ordered all students from the country to remain at one location at the base, authorities said.

'There are a number of Saudi students who are close to the shooter and continue to cooperate in this investigation,' Rojas said.

'The Saudi government has pledged to fully cooperate with our investigation.'

Florida Governor Ron DeSantis said the investigation was proceeding under 'the presumption that this was an act of terrorism' and he called for better vetting of foreigners allowed into the US for training on American bases.