SAN BERNARDINO, Calif. (CN) - Federal and San Bernardino authorities on Tuesday appealed to the public to help them unravel the mystery of 18 minutes that elapsed immediately after last month's massacre at the Inland Regional Center.
Syed Rizwan Farook and Tashfeen Malik killed 14 and wounded another 22 at the mass shooting they carried out at a San Bernardino Dept. of Public Health holiday party, but so far, law enforcement has been stymied in its attempts to piece together a chuck of time immediately after the killers left the facility.
On Tuesday afternoon, FBI Assistant Director David Bowdich asked the public to come forward with any information that could help them as they continue to investigate the motives of Farook and Malik, and whether they were helped by anyone not yet in custody.
Bowdich said investigators have accounted for 3 hours and 42 minutes of time before, during and after the shooting.
"We are missing 18 minutes of their time," Bowdich said.
He said authorities want to know if the couple made any stops at businesses or residences or had spoken to anyone during that time.
"There's no evidence that they stopped anywhere," Bowdich said, but he later added that the couple may have stopped at a parking garage and then a lake, the latter of which was searched by authorities last month.
Bowdich asked members of the public with photographic, video or other information about the case, but who have not already been in contact with law enforcement, should to call 1-800-CALL-FBI, and choose Option 4.
Investigators have determined Farook left home at 8:37 a.m. the day of the attacks and arrived at the Inland Regional Center about 10 minutes later.
They said he left the party at 10:37 a.m., leaving a jacket hanging on the back of a chair, and returned with Malik to commence the attack at 10:56 a.m.
It's not known where Malik was when her husband initially arrived at the center, but investigators believe she was waiting in the couple's SUV outside.
According to Bowdich, there is no evidence to suggest that the attack stemmed from a workplace dispute. He noted that Farook had appeared in photos taken at the event before he returned to the center and carried out the attack.
The couple was later shot dead by police after a gun battle in the streets and authorities tailed their 2015 Black Ford Expedition.
Authorities are seeking more information on the couple as well as the vehicle which had dark tinted windows, a roof rack, chrome accent on the rear gate and a Utah license plate.
The only individual charged in the investigation is Enrique Marquez Jr., a longtime friend of Sayed Rizwan Farook, who authorities say conspired to provide material support to terrorists by helping Farook buy two assault rifles used in the shooting.
Farook was a U.S. citizen, born in Chicago to Pakistani parents. Malik was a Pakistani national.
Though authorities have uncovered some evidence the couple supported the objectives of Islamic State terrorists, the motives that drove the attack remain unclear.
There is no evidence to suggest they were directed by Islamic extremists, Bowdich said.
"We definitely believe that this was an inspired act. We do not have an indication of a foreign directed attack, as of today," Bowdich said.
Marquez told investigators in December that he bought the assault weapons two years ago when he and San Bernardino gunman Syed Rizwan Farook were planning attacks on the Riverside Community College and State Route 91.
By that time, Farook had exposed Marquez to Islamic extremist content including videos and other publications, prosecutors say.
Marquez is scheduled enter a plea at the Riverside federal court on Wednesday morning.
San Bernardino Police Chief, Jarrod Burguan and San Bernardino County Sheriff, John McMahon also spoke during the press briefing.
McMahon said the cost to county of responding to the terror attack was $4 million.
Patti Martus, of Courthouse News' San Bernardino bureau, contributed to this report.
Read the Top 8
Sign up for the Top 8, a roundup of the day's top stories delivered directly to your inbox Monday through Friday.