Saudi authorities are investigating whether the Pensacola navy base killer was radicalized during a trip home last year, according to a report Sunday.

Mohammed Saeed Alshamrani, who killed three young US Navy students in Friday’s shooting spree in Florida, had been in the US since 2017 for a Pentagon training program, according to the Wall Street Journal.

The 21-year-old Saudi Air Force lieutenant had returned home for a trip last year, sparking fears that he could have been radicalized there before returning to the US in February this year, the paper said.

Authorities in the kingdom are trying to determine how Alshamrani spent his time and whom he contacted during his trip in late 2018, officials told the paper.

Alshamrani watched mass-shooting videos with at least three of his countrymen at a dinner party before the shooting, which his friends are understood to have filmed.

A spokesman for Saudi Arabia’s embassy in Washington did not respond to the paper’s request for comment.

A series of tweets attributed to Alshamrani hours before the attack claimed he hated the American people for “committing crimes not only against Muslims but also humanity,” according to SITE Intelligence Group, which monitors online Islamist extremism.

The tweets — which have yet to be verified — also quoted Osama bin Laden, the Saudi mastermind of the 9/11 terror attacks, according to SITE. Twitter suspended the account but did not confirm it belonged to the killer.

The base outside Pensacola, near Florida’s border with Alabama, is a major training site for the Navy and employs about 16,000 military and 7,400 civilian personnel.

With Post wires