Syed Rizwan Farook

On February 9, 2016, the FBI announced that it was unable to unlock one of the mobile phones they had recovered from Farook and Malik's home because of the phone's advanced security features. The phone was an iPhone 5C owned by the county and issued to Farook during his employment with them. When asked by the FBI to create a new version of the phone's iOS operating system that could be installed and run in the phone's random access memory to disable certain security features, Apple Inc. declined due to its policy to never undermine the security features of its products. The FBI responded by successfully applying to a United States magistrate judge to issue a court order under the All Writs Act of 1789, mandating Apple to create and provide the requested software. Citing security risks posed towards their customers as a result of such software, Apple announced their intent to oppose the order, resulting in a dispute between the company and the FBI. The dispute eventually ended on March 28, 2016, when the U.S. Department of Justice announced that it had unlocked the iPhone.

The San Bernardino County Sheriff’s Department released autopsies for the 14 victims on May 27, 2016. More than three years after the attack however, autopsy reports for Farook and Malik had yet to be made public. The department responded to an April 12, 2017 Public Records Act request stating, "Currently, the autopsy reports and coroner investigations, and all other law enforcement records pertaining to the death of Syed R. Farook and Tashfeen Malik, are part of an 'investigatory file,' and are exempt from disclosure."

On May 31, 2016, federal prosecutors filed a lawsuit against Farook's family. This lawsuit would allow them to seize both the proceeds of two life insurance policies (and the policies themselves) held by Farook, both of which listed Farook's mother as the beneficiary. One policy worth US$25,000 was taken out by Farook in 2012 when he started working for the county, while the other, worth US$250,000 , was taken out the following year. According to NBC News, "Under federal law, assets derived from terrorism are subject to forfeiture. A federal judge must approve an application before the government can seize the money." In the six-page lawsuit, the life insurance company claimed that Farook's mother was aware of her son's intentions to carry out the attack, and reasoned that she should not be entitled to the benefits as a result. On September 2, 2016, government officials said they wanted to give the money to the victims' families.

On December 16, 2015, FBI Director James Comey said, "We can see from our investigation that in late 2013, before there is a physical meeting of these two people [Farook and Malik] resulting in their engagement and then journey to the United States, they are communicating online, showing signs in that communication of their joint commitment to jihadism and to martyrdom. Those communications are direct, private messages."

In Senate Judiciary Committee testimony given on December 9, 2015, FBI Director James B. Comey said that the FBI investigation has shown that Farook and Malik were "homegrown violent extremists" who were "inspired by foreign terrorist organizations." Comey also said that Farook and Malik "were talking to each other about jihad and martyrdom," before their engagement and as early as the end of 2013. They reportedly spent at least a year preparing for the attack, including taking target practice and making plans to take care of their child and Farook's mother. Comey has said that although the investigation has shown that Farook and Malik were radicalized and possibly inspired by foreign terrorist organizations, there is no indication that the couple were directed by such a group or part of a broader cell or network.

The two rifles were purchased by Enrique Marquez Jr., a next-door neighbor of Farook's until May 2015 who is related to him by marriage. After their purchases, the rifles were illegally transferred to Farook. The two pistols were legally purchased by Farook from federally licensed firearms dealers in Corona, California in 2011 and 2012. One of the handguns was a Llama Model XI-B and the other was a Springfield Armory XD Bi-Tone.

Two weeks before the shooting, Farook took out a loan of US$28,500 which was deposited in his bank account. The San Francisco-based online lender Prosper Marketplace made the loan to Farook; Prosper evaluates borrowers and the loans are originated by a third-party bank, the Salt Lake City-based WebBank.com. On or about November 20, 2015, Farook withdrew US$10,000 in cash, and later on two US$5,000 transfers were made to what appears to be Farook's mother's bank account. Investigators were exploring the possibility that the US$10,000 was used to reimburse someone for the purchase of the rifles used in the shooting. WebBank said that it was fully cooperating with the investigation.

After Farook and Malik's corpses were released by law enforcement, local Islamic cemeteries refused to accept the remains. It took a week to find a willing cemetery, and the burial ultimately took place in Rosamond, California. According to two members of the mosque, many of the city's Muslim community refused to attend the funeral on December 15, 2015, which was attended by around ten mourners including relatives of Farook.

In one Arabic-language online radio broadcast, ISIL described Farook and Malik as "supporters" following the attack. During the police investigation into the attack, The New York Times reported that this language indicated "a less direct connection" between the shooters and the terrorist group. In a December 5, 2015, English-language broadcast on its Bayan radio station, ISIL referred to Farook and Malik as "soldiers of the caliphate," which is a phrase ISIL uses to denote members of the terrorist organization. The New York Times reported that it was unclear why the two versions differed.

According to one of Farook's coworkers, Malik and her husband married about a month after he traveled to Saudi Arabia in early 2014; the two had met over the Internet. Malik joined Farook in California shortly after their wedding. A U.S. marriage certificate reported their marriage in Riverside on August 16, 2014. At the time of her death, Malik and Farook had a six-month-old daughter.

Malik entered the United States on a K-1 (fiancée) visa with a Pakistani passport. According to a State Department spokesman, all applicants for such visas are fully screened. Malik's application for permanent residency (a "green card") was completed by Farook on her behalf in September 2014, and she was granted a conditional green card in July 2015. Obtaining such a green card would have required the couple to prove that the marriage was legitimate. As is standard practice, as part of her visa application with the State Department and application for a green card, Malik submitted her fingerprints and underwent "three extensive national security and criminal background screenings" using Homeland Security and State Department databases. Malik also underwent two in-person interviews, the first with a consular officer in Pakistan and the second with an immigration officer in the U.S. after applying for a green card. No irregularities or signs of suspicion were found in the record of Malik's interview with the Pakistani consular officer.

According to family members and coworkers, Farook was a devout Sunni Muslim, and traveled to Saudi Arabia several times, including to complete the hajj in 2013. Farook attended prayers at the Islamic Center of Riverside twice a day, in the mornings and the evenings, according to an interview in The New York Times with Mustafa H. Kuko, the Center's director. According to the Times, Farook stood out as especially devout and "kept a bit of a distance" from other congregants. During that time, according to friends, he never discussed politics. Farook abruptly stopped going to the mosque in 2014 following his marriage.

The Italian newspaper La Stampa reported that Farook's father said that his son "shared the ideology of Al Baghdadi to create an Islamic state" and that he was fixated with Israel. A spokesperson for the Council on American–Islamic Relations (CAIR) later claimed the father did not recall making these statements about his son.

While in Multan, Malik attended the local center of the Al-Huda International Seminary, a women-only religious academy network with seminaries across Pakistan and branches in the U.S. and Canada that was founded in 1994. The school is aligned with the Wahhabi form of Sunni Islam. According to school records, Malik enrolled in an eighteen-month Quranic studies course with Al-Huda on April 17, 2013, and left on May 3, 2014, telling administrators that she was leaving to get married. Malik expressed an interest in completing the course by correspondence, but never did so.

After law enforcement sources confirmed that Farook spent time on November 29–30, 2015, at the Riverside Magnum Shooting Range, about 25 miles (40 km) away from the couple's Redlands home, the FBI obtained surveillance video from the range. During these visits, one lasting several hours, Farook shot an AR-15 and a pistol, which he had brought to the range. One of the paper torso silhouette targets used in the video was later recovered from the couple's SUV following their deaths.

Farook worked as a food inspector for the San Bernardino County Department of Public Health for five years before the shooting. From July to December 2010, he was a seasonal employee for the county. He was hired as an environmental health specialist trainee on January 28, 2012, and became a permanent employee on February 8, 2014. Coworkers described Farook as quiet and polite, and said that he held no obvious grudges. Two weeks before the attack, he reportedly tried to explain, during an office conversation, that Islam was a peaceful religion.

Malik returned to Pakistan to study pharmacology at Bahauddin Zakariya University in Multan, beginning the program in 2007 and graduating in 2012. Saudi Interior Ministry spokesman Major General Mansour Al-Turki denied reports that Malik grew up in his country, saying that she only visited Saudi Arabia for a few weeks in 2008 and again in 2013. The city of Multan has been linked to jihadist activity.

According to sources, Farook had a "troubled childhood" and grew up in an "abusive" home in which his father was often violent towards his mother. Farook grew up in Riverside, California, and attended La Sierra High School, graduating in 2004, one year early. He attended California State University, San Bernardino, and received a bachelor's degree in environmental health in either 2009 or 2010. He was a student for one semester in 2014 at California State University, Fullerton in their graduate program for environmental engineering, but never completed the program.

Syed Rizwan Farook (June 14, 1987 – December 2, 2015) and Tashfeen Malik (July 13, 1986 – December 2, 2015) were the two perpetrators of a terrorist attack at the Inland Regional Center in San Bernardino, California, on December 2, 2015. In the attack, they killed 14 people and injured 22 others. Both died in a shootout by law enforcement later that same day.

The attack was the second-deadliest mass shooting in California after the 1984 San Ysidro McDonald's massacre. It was also the deadliest mass shooting in the U.S. since the 2012 Sandy Hook Elementary School shooting, and the deadliest terrorist attack to occur in the U.S. since the September 11 attacks, until both categories were surpassed by the 2016 Orlando nightclub shooting six months later. Malik was one of a small number of female mass shooters in the U.S.; women constituted only 3.75 percent of active shooters in the U.S. from 2000 to 2013.