Australian extremist Brenton Tarrant has emerged as a central inspiration in the San Diego mosque shooting which left three innocent people dead.
Cain Clark, 17, attacked the Islamic Center of San Diego alongside Caleb Vazquez, 18, around 11.40am on Monday, after apparently stealing guns and a car from his home.
Hours before the attack, Clark's mother reported to police that her son was at risk of self-harm and was potentially armed with weapons.
After killing three people, the teenagers were found in a car near the mosque with self-inflicted gunshot wounds.
The FBI said the reclusive pair had met online and bonded over white supremacist rantings and their alleged Nazi leanings.
A 75-page manifesto that was shared online included Nazi images, misogyny, and racist statements about black people and other minorities. According to officials, the writings are filled with anti-Islamic, antisemitic and anti-LGBTQ views.
The teens described Tarrant as one of their heroes and inspirations for the attack, and described themselves as the 'Sons of Tarrant'.
Tarrant, an Australian national, who carried out attacks on two mosques in Christchurch, New Zealand, on March 15, 2019, killing 51 worshippers during prayers.
Cain Clark, 17, attacked the Islamic Center of San Diego alongside Caleb Vazquez, 18, around 11.40am on Monday, after apparently stealing guns and a car from his home
Caleb Vazquez (pictured) opened fire alongside Clark in the shooting on Monday, killing three people before they turned their guns on themselves
Brenton Tarrant (pictured) the Christchurch shooter is credited as inspiration for the shooting
The manifesto positions Tarrant as a defining figure in modern extremist movements, portraying the Christchurch massacre as a catalyst for further violence.
The most extensive section is dedicated entirely to Tarrant who is described as suspects' biggest inspiration' and a 'true revolutionary'.
Tarrant pleaded guilty and was sentenced to life imprisonment without parole, the first such sentence in New Zealand's history.
On April 30, the New Zealand Court of Appeal unanimously dismissed Tarrant's bid to overturn his convictions.
The court ruled his attempt to abandon his guilty pleas was 'utterly devoid of merit,' finding that his claims of being mentally unfit and coerced were contradicted by prison and medical records.
Security experts have warned that Tarrant's manifesto and footage from the attack continue to circulate in extremist online spaces, where they are used as propaganda to radicalise and inspire others.
FBI official Mark Remily said authorities are still working to determine whether the suspects intended further attacks.
Searches linked to the investigation uncovered a large cache of weapons, including 30 firearms and a crossbow.
The writings also referenced other mass killers as sources of inspiration, including Elliot Rodger, who carried out the 2014 Isla Vista killings in California, and Ted Kaczynski, the so‑called 'Unabomber', who waged a years‑long mail bombing campaign across the United States that killed three people and injured dozens.