Syed Farook and Tashfeen Malik, the suspects involved in the San Bernardino massacre that left 14 people dead and 21 injured, may have been looking at Islamic State (ISIS) propaganda before committing the atrocity, it has been reported.

On 2 December, the attackers opened fire in a conference area where a Christmas party for staff of the San Bernardino County's public health department was underway, at the Inland Regional Centre training. Farook, a local government employee, was in attendance but left early after a dispute. He returned later with his wife dressed in tactical-style gear and opened fire on the gathering. Following a manhunt, Farook and Malik were eventually shot dead by police on San Bernardino Avenue.

CBS and CNN are reporting that the couple used "ISIS tactics" in what has been described as a "classic case" of an IS inspired attack. Robert Baer, CNN intelligence and security analyst, said he believes 28-year-old Farook and his 27-year-old wife may have received combat training. "The tactics that they adopted in taking down this place were exactly ISIS tactics," Baer told CNN. "Now I'm not saying ISIS was behind this, inspired it, they haven't claimed it or anything like that, but the tactics suggest they were taught in the Middle East or they simply were on websites and got some sort of training. These are not people that just got mad at their employer and shot the place up. I just don't see that right now."

Investigators are exploring possible connections between Farook and his wife to terror groups abroad to determine whether they were acting on orders from fundamental jihadist groups. The FBI have reportedly said they uncovered evidence that Farook was in contact with domestic and international extremists by phone and via social media and had travelled to Saudi Arabia and possibly also to Pakistan.

It is know that Farook, who was born in the U.S. to a Pakistani family and raised in Southern California, travelled to Saudi Arabia in 2013 for the hajj pilgrimage to Mecca. It is believed that he first met Malik on an online dating site and during his stay abroad, the pair were engaged. He later brought the Pakistan native over to the US on a K-1 fiancee visa.

Meanwhile, residents of the sleepy town of Redlands expressed their shock that their neighbours might have been mass killers, as locals recall suspicious activity that had gone unreported. A man who has been working in the area said he noticed half a dozen Middle Eastern men in the area in recent weeks, but decided not to report anything since he did not wish to racially profile them. "We sat around lunch thinking, 'What were they doing around the neighborhood?'" he said. "We'd see them leave where they're raiding the apartment."

Another neighbour reported that Farook and Malik were apparently working late at night in their garage and receiving numerous packages to their home. But, according to nearby residents, they did not report them for fear of racial profiling. It has since emerged the couple had 12 pipes bombs, a stock pile of tools to assemble explosives, 2,000 9mm rounds, and over 2,500 223 rounds in their suburban home.

Colleagues said Farook was a devout Muslim but had never voiced any radical views.