FBI agents said they have yet to figure out what Syed Rizwan Farook and his wife, Tashfeen Malik, were doing for a critical chunk of time - 12:59 pm to 1:17 pm on December 2 after they killed 14 people and injured many more at the Inland Regional Center in San Bernardino.
When Farook and Malik resurfaced, they were over one km from the center, which at that time was flooded with paramedics, police, reporters and family members frantically searching for loved ones.
"We're dark," he said yesterday.
He said the couple's route involved "a lot of zigzagging around, going back and forth on the highway. There is no rhyme or reason to it that we can find yet."
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Filling in that missing link would help investigators determine whether Farook and Malik stopped at any homes or businesses or met with anyone else after the attack, Bowdich was quoted as saying by Los Angles Times.
The couple seemed in no hurry to flee the city. They briefly pulled over near Seccombe Lake and in a parking lot near the Inland Regional Center.
The FBI has previously said the couple appeared to have embraced radical Islamic teachings and had been radicalised "for quite some time."
Bowdich said the investigation had turned up no evidence that the attack was orchestrated from abroad.
"This seems to be an inspired terrorist act," he said.
The FBI has declined to say where Farook went after he left. But the law enforcement official said investigators do not believe Farook would have had time to go back to his Redlands home before the attack.
The investigation shows that both AR-15 assault rifles used by the couple were fired inside the conference room where the victims were shot, the law enforcement source said.
After fleeing in the SUV, the couple drove through parts of San Bernardino and Redlands - pausing at the lake about 11:45 am. Bowdich said a search of the lake had not turned up anything of value to the investigation.