By Sarah N. Lynch and Mark Hosenball

WASHINGTON (Reuters) – The FBI has found cellphone evidence linking al Qaeda to the Royal Saudi Air Force trainee who killed three American sailors and wounded eight people in a December shooting spree at a U.S. naval base in Florida, a federal law enforcement source said on Monday.

The shooter, Second Lieutenant Mohammed Saeed Alshamrani, 21, was killed by law enforcement during the Dec. 6, 2019 attack.

He was on the base as part of a U.S. Navy training program designed to foster links with foreign allies.

Since then, the Justice Department has been working to try and unlock the encryption on the shooter’s phone to get a better sense of his motives and whether he had connections to known terrorist groups.

In February, an audio recording purporting to be from the Islamist militant group al Qaeda in the Arabian Peninsula (AQAP) claimed responsibility for the fatal attack, but it provided no evidence.

Prior to the shooting spree, the shooter also posted criticism of U.S. wars and quoted slain al Qaeda leader Osama bin Laden on social media.

The Justice Department has also previously said that Alshamrani visited the New York City memorial to the victims of the Sept. 11, 2001, attacks on the United States – carried out by Saudi hijackers for the Islamist militant group al Qaeda – and posted anti-American, anti-Israeli and jihadi messages on social media, including two hours before the attack.

The FBI’s newly discovered evidence on Alshamrani’s phone signals the end of a spat between Attorney General William Barr and Apple Inc.

Earlier this year, he accused Apple of failing to help the FBI to get Alshamrani’s two cellphones unlocked, an allegation Apple staunchly denied.

Barr has said the Saudi government did not have any advanced warnings of the shooting.

However, in January, Saudi Arabia withdrew its remaining 21 cadets from the U.S. military training program and brought them back to Saudi Arabia, after the Justice Department’s investigation revealed that some of them had accessed child pornography or had social media accounts containing Islamic extremist or anti-American content.

(Reporting by Mark Hosenball and Sarah N. Lynch; additional reporting by Susan Heavey; Editing by Chizu Nomiyama and David Gregorio)