San Bernardino police and the FBI are pointing to the Christmas theme at a work holiday party as one spark that two terrorists latched onto as a motive for their long-planned Islamic terror attack.

The first anniversary of the attack is Dec. 2.

Syed Rizwan Farook brought Pakistani woman Tashfeen Malik to the United States on a K-1 finance visa in July 2014 and married her. Not a year-and-a-half later, the two shot and killed 14, and injured 22, at the holiday party on December 2, 2015.

The FBI and police investigation into the massacre brought to light emails from Malik. Those emails revealed her disdain for the party’s Christmas setting, which was planned for the holiday luncheon put on by her husband’s employer. The holiday luncheon was set to follow a work training that Farook was being required to attend according to ABC News.

San Bernardino police chief Jarrod Burguan told the media outlet, “She had essentially made the statement in an online account that she didn’t think that a Muslim should have to participate in a non-Muslim holiday or event.” Burguan called this one of very, very few pieces of evidence that point to a probable motive for the attack.

Evidence surfaced within days of the attack that the two had been planning some form of assault for around a year.

The investigation also revealed that Farook had practiced shooting at a firing range just two days before the attack. Burguan told ABC News that the two had high powered weaponry, lots of ammunition and “bombs at their disposal.”

Following the attack, the Islamic terrorist couple stayed close to, and repeatedly drove by, the attack site for over four hours. It is now believed that they tried repeatedly to detonate three pipe bombs that they had planted in the building.

Ultimately, the two were killed in a shootout with law enforcement. A remote detonator was found in the vehicle in which the two made their last stand.

Farook had planned a maximum casualty Islamic terror attack years earlier, around 2012, with friend and Muslim convert Enrique Marquez. The two ultimately abandoned their plans in light of terror arrests at the time. Marquez has been charged as a straw purchaser of two rifles he provided to the terrorists that were used in the attack. Marquez has also been charged with marriage fraud. (He married a Russian woman in 2014 and the Russian woman’s sister married Farook’s brother.)

Though investigators are placing blame on the holiday party, evidence shows that the couple had been stockpiling weaponry. One mystery that haunted authorities from early on was the presence of unused bombs found in the couple’s apartment after the attack was over and the married couple were dead.

Farook had taken out life insurance policies in 2012, the year Marquez and Farook had been planning an attack, and in 2013. The life insurance proceeds total a combined $275,000 in coverage. Court filings in the case for the federal government to seize the insurance funds cite the early terror plot plans of Farook and Marquez.

Breitbart News previously reported, “Documents also detailed Farook’s discussions of 9/11 linked Islamic terrorist Anwar al-Awlaki (listed in the documents as al-Aulaqi) and alleges that Farook and Marquez were “inspired by the acts of Muslim Army Major Nidal Hasan, who shot and killed 13 people and injured more than 30 at Fort Hood, Texas on November 5, 2009.””

Farook attended the Dar Al Uloom Islamiyah mosque, which has been tied to the fundamentalist Tablighi Jamaat (TJ) sect of Islam. The TJ sect has been referred to as the “Army of Darkness.” CBS News reported that Farook and Malik held their wedding reception at the mosque.

Follow Michelle Moons on Twitter @MichelleDiana