Story highlights

Investigators are unsure where Syed Rizwan Farook and Tashfeen Malik were on December 2 from 12:59 p.m. to 1:17 p.m.

FBI asks for public's help in completing the timeline

Farook and Malik spent much of the time after the massacre driving back and forth on the interstates

CNN  — 

Federal investigators piecing together a timeline of the movements of San Bernardino shooters Syed Rizwan Farook and Tashfeen Malik need help accounting for 18 minutes on the afternoon after the deadly attack.

“We want to ensure that if they made contact with anyone that we don’t already know about between those hours or between that time that we’re able to fully investigate those matters,” said David Bowdich, the director of the FBI’s Los Angeles office, in appealing to the public for assistance.

Bowdich made it clear the FBI doesn’t know what happened between 12:59 p.m. and 1:17 p.m. on December 2 nor the importance of that time. He gave some possibilities – Farook and Malik could have stopped at a storage unit, a business or a home – and said the 18 minutes were a gap in the time line officials want to close.

Investigators have accounted for three hours, 42 minutes, beginning with Farook leaving his apartment at 8:37 a.m. The timeline ends with the suspects killed about 3 p.m. in a shootout with police

It’s all part of determining the motive for the attack, Bowdich said. There are no indications the massacre of 14 people at a meeting at the Inland Regional Center was directed by anyone overseas, but it was an inspired attack, he said.

The timeline is a product of more than 500 interviews and watching surveillance video.

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Bowdich said Farook arrived at the meeting at 8:47 a.m. and he left at 10:37 a.m., leaving behind a book bag containing pipe bombs.

He returned with Malik, his wife, at 10:56 a.m., shooting people outside the room and then bursting through the door. They killed 14 people and wounded 22 others.

Bowdich said Farook and Malik then spent a lot of time driving back and forth in an area near the shooting.

Authorities can account for at least two stops.

At 11:45 a.m., they stopped at a small lake in a park north of the shooting. Authorities searched the lake for several days last month but found no evidence tied to the shootings.

After the lake visit, they resumed driving and at 12:59 they went dark, Bowdich said, for 18 minutes.

There was also a parking lot stop, but Bowdich didn’t give any details.

He asked people who think they have information about where Farook and Malik might have been during that time to call 1-800-CALLFBI (1-800-225-5324).

Authorities asked people to check their cell phone images and for business operators in the area to recheck surveillance video.

Police detectives looking for Farook saw the couple at 2:52 p.m. That led to a chase and a shootout in which the terrorists were killed minutes later.

While it is unclear why Farook and Malik were driving back and forth, mostly on interstates, Bowdich said there is no evidence there were secondary targets, though that has not been ruled out.