An internal report compiled by the Saudi government has concluded that Mohammed Saeed Alshamrani, the Saudi Air Force trainee who killed three and injured eight, appears to have been radicalized years before arriving in the US

The Saudi Air Force officer who killed three American sailors and injured eight others at Naval Air Station Pensacola last week appears to have been radicalized by hardliner clerics years before arriving in the US as part of a training program.

Second Lieutenant Mohammed Saeed Alshamrani, 21, was shot and killed by Florida sheriff's deputies on Friday, after he opened fire on the naval base using a legally purchased handgun.

The Washington Post reported on Wednesday, citing an internal report compiled by the Saudi government, that a Twitter account attributed to Alshamrani indicates that the aviation student had been expressing 'extremist' thoughts as early as 2015, two years before he arrived in the US for training.

Based on his social media activity at the time, Alshamrani had fallen under the influence of four radical Muslim clerics and activists, among them Saudis Abdulaziz al-Turaifi and Ibrahim al-Sakran, Kuwaiti national Hakim al-Mutairi, and Jordan's Eyad Qunaibi.

Until then, the teenage Alshamrani's tweets and retweets were mostly limited to poetry and inspirational verses from the Koran, but in late 2015, when he was about 17 years old, his posts took on a political tone.

The Saudi analysis stated that Alshamrani had retweeted one tweet from Turaifi, in which the preacher with more than one million Twitter followers is 'decrying the Kingdom of Saudi Arabia’s alliance with the United States whom Al-Turaifi considers "the enemy.”'

Around 2015, Alshamrani, then a teenager, retweeted a tweet from radical Muslim cleric Abdulaziz al-Turaifi (pictured), in which he called the US 'the enemy'

Alshamrani also reportedly retweeted tweets from Kuwaiti Hakim al-Mutairi (pictured), who called for a jihad on American and Israeli 'crusaders'

Alshamrani also was said to have retweeted tweets from Mutairi, which called for 'jihad' against American and Israeli 'crusaders.'

'His retweets and likes in general heavily favored religious accounts that advocated for jihad and defended jihadists who proselytized against both the West and Western-allied Muslim governments alike,” the report said.

According to the report, Alshamrani had used his now-defunct Twitter account to endorse radical Islam and terrorism, rail against America and Israel, and express support for the Afghan Taliban.

The Saudi analysis stresses that Alshamrani's Twitter account was under the name 'Mohammed,' which is very common in the Kingdom, and it lacked a profile photo or any biographical details that would have facilitated the user's identification.

It was not until Alshamrani posted a manifesto on his account, just hours before the attack in Florida, that officials connected the dots.

The aviation student's screed invoked purported 'crimes against Muslims,' blasted the US government for supporting Israel and brought up the notorious prison at Guantanamo Bay, Cuba.

In was previously reported Alshamrani had a disturbing change in personality after returning from his native country in the weeks leading up to the deadly violence.

School mates and others who knew the 21-year-old man, said he returned from Saudi Arabia acting 'strange' and 'angry'.

The owner of an Indian restaurant frequented by Alshamrani said 'he looked like he was angry at the world,' upon his return.

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 US Naval Academy (right)

The restaurant owner asked that he and his business not to be identified, for fear of a backlash for speaking publicly, the Washington Post reports.

Alshamrani was alleged to have opened fire inside a classroom at Naval Air Station in Pensacola early Friday morning.

Using a Glock 9mm handgun he'd purchased by exploiting a legal loophole, Alshamrani opened fire in a classroom at the base, killing Airman Mohammed Sameh Hathaim, 19, Ensign Joshua Kaleb Watson, and Airman Apprentice Cameron Scott Walters, 21.

Eight others, including two deputies, were wounded in a gunfight with Alshamrani, who was later shot dead by police.

The victims and survivors may become candidates for the Purple Heart, if the attack was deemed inspired by a terrorist organization, according to the award's guidelines.

That question has yet to be determined by authorities.

What they did learn was that days before the gunfire erupted, Alshamrani hosted a dinner party for himself and three other Saudi trainees where they all watched videos of mass shootings together.

He also was found to have penned a hate-fueled manifesto on Twitter just hours before the violence erupted, according to an intelligence group who tracked down his account.

Alshamrani had been a second lieutenant in the Saudi Air Force attending aviation school at the base. The Pentagon says his training with the US military began in August 2016, and was due to finish in August 2020.

An Air Force carry team moves a transfer case containing the remains of Navy Ensign Joshua Watson on Sunday at Dover Air Force Base, Delaware

An Air Force carry team moves a transfer case containing the remains of Navy Seaman Mohammed Sameh Haitham, of St. Petersburg, Fla., Sunday, at Dover Air Force Base, Delaware

Acting Navy Secretary Thomas Modly, center, and Navy Admiral Michael Gilday, Chief of Naval Operations, right, the remains of Navy Seaman Apprentice Cameron Scott Walters, of Richmond Hill, Georgia, arrive at Dover Air Force Base, Delaware, on Sunday

A Saudi government official who knew Alshamrani offered a stark contrast to the alleged-hate filled person who has emerged from the investigation so far.

The official said Alshamrani was a top student, who was 'well-liked and kept to himself', the Post reports.

The official also said that the Saudi government had been unaware Alshamrani filed a formal complaint against one of his instructors who 'infuriated' him with a derogatory nickname, 'Porn Stash' in front of his fellow classmates, the New York Times reports.

The FBI declined to comment on the alleged comment made by the instructor.

The good-natured persona used to describe him was echoed by others who spoke with investigators, reports the Washington Post, including classmates who said he was quiet, reserved and rarely spoke in class.

His demeanor, however, changed they said after the trip to Saudi Arabia. The owner of a Pensacola eatery that Alshamrani visited once a week said he was 'strange', 'quiet' and angry'.

'To us, he was not normal,” the eatery owner said.

He recalled Alshamrani staring at him and his staff in an “angry, challenging” way.

But there was no sign of religious extremism. For example, he didn't ask if the restaurant served halal meat, which is eaten by observant Muslims.

The owner of the Indian restaurant said Alshamrani was one of seven or eight Saudis who visited his restaurant up to two times per week, usually after Friday prayers, the Washington Post reports.

Several business owners said they were questioned by law enforcement after the shooting. None of the people who said they knew Alshamrani recalled him discussing religion or politics.

His Twitter account, however, did reveal that he assailed the United States as 'a nation of evil' just before his shooting rampage.

On Friday evening, the SITE Intelligence Group, which monitors jihadist media, claimed they had tracked a Twitter account belonging to Alshamrani which featured a disturbing manifesto written just hours before the shooting.

'I'm against evil, and America as a whole has turned into a nation of evil', it read.

'I'm not against you for just being American, I don't hate you because your freedoms, I hate you because every day you supporting, funding and committing crimes not only against Muslims but also humanity', Alshamrani wrote.

ABC News reported that investigators were working to determine if if the tweet was in fact written by the shooter.

The Twitter account that posted the manifesto - which also condemned US support for Israel and included a quote from Al-Qaeda's deceased leader, the Saudi Osama bin Laden - has now been suspended.