LOS ANGELES (Reuters) - One year after two Islamic militants shot dead 14 people in a massacre in Southern California, FBI investigators are still seeking to answer key questions such as the location of the married couple’s computer hard drive and whether anyone helped them, an official said.

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Syed Rizwan Farook, 28, and his wife, Tashfeen Malik, 29, opened fire on Dec. 2 during a party and training session for San Bernardino County employees, who were co-workers of Farook, injuring 22 people in addition to the 14 killed.

It was one of the deadliest attacks by militants in the United States since the Sept. 11, 2001, hijacked plane attacks.

Authorities have said that U.S.-born Farook and Malik, a native of Pakistan who lived most of her life in Saudi Arabia, were inspired by Islamic extremism. The couple, who were parents of a 6-month-old daughter, both died in a shootout with police four hours after the massacre.

The Federal Bureau of Investigation is still seeking to determine if anyone assisted the couple, such as in financing the attack or helping to plan for it, FBI spokeswoman Laura Eimiller said.

“While we have not charged anyone with providing support to Farook and Malik, we certainly will continue to investigate to determine if they were supported in any way,” she said in a telephone interview.

To that end, the FBI is still hoping to find the hard drive from the couple’s computer, Eimiller said.

A search by FBI divers in the weeks after the attack of a small lake at a park where Farook and Malik stopped in the hours after the shooting failed to turn up the hard drive.

In addition, the FBI still has an 18-minute gap in accounting for the whereabouts of Farook and Malik in the hours they spent driving around San Bernardino in a sport utility vehicle after the attack at the city’s Inland Regional Center.

The couple left three pipe bombs at the center, in an apparent attempt to harm emergency workers caring for the wounded, according to authorities. The couple approached the center after the attack and might have been trying to detonate one of the devices remotely, Eimiller said.

Several public events are scheduled for Friday in San Bernardino to mark the one-year anniversary of the attack.

Elected officials and emergency responders who handled the attack will attend a ceremony at a San Bernardino blood bank on Friday morning. In the evening, another event is expected to draw at least 2,000 participants to an arena in the city.