WASHINGTON — The CIA is adding operatives and resources to focus on the Somalia-based militant group the Shabab as the FBI sends scores of agents to help examine evidence taken from the rubble of the shopping mall massacre in Nairobi, U.S. officials say.

The FBI is taking the lead in the investigation, while the CIA and other U.S. intelligence agencies are mining electronic data and quizzing informants in an effort to determine whether the Al Qaeda-linked group is planning new attacks, including any against U.S. facilities or interests.


The CIA’s counter-terrorism center has several analysts and operatives who work full time on the Shabab, but they had detected no sign that the audacious attack in Kenya’s capital was being planned. The center will add experts to step up collection and analysis of intelligence on the group’s leaders and operations.

The FBI team in Nairobi has begun collecting DNA, fingerprints and other biometric information to try to identify the gunmen and victims, officials said, and is studying data from cellphones, surveillance video and other digital sources that might shed light on the four-day siege at the Westgate mall, which left more than 70 people dead and dozens wounded or missing.


Agents from the FBI’s field office in New York and its Joint Terrorism Task Force also are examining the financing of the plot, and are seeking to determine whether anyone who did not participate in the attack helped choose the target or otherwise coordinate it. The FBI eventually hopes to prepare a timeline that shows how the assault was planned, funded and executed.

“There’s a lot to learn here,” said an FBI agent who spoke on condition of anonymity because the investigation was underway. “We want to get all we can.”


The State Department issued a “worldwide caution” regarding the potential for further terrorist attacks. It specifically accuses the Shabab of “assassinations, suicide bombings, hostage taking and indiscriminate attacks in civilian-populated areas” of Somalia and nearby East African nations, including attacks on humanitarian aid groups.

U.S. officials long considered the militant Islamist group a regional danger but not a specific threat to America. That assessment is now under review.


“We are taking [the threat] as a serious one,” Atty. Gen. Eric H. Holder Jr. told reporters Thursday.

“I would not say that we have any specific, credible evidence that the Shabab is planning to do anything in the United States,” he added. “I’m not sure if they have the capacity to do anything in the United States.”


But the FBI is concerned about the Shabab’s success in recruiting Somali Americans to its cause. More than 20 are believed to have traveled to the Horn of Africa to join the group, which has long fought an insurgency in Somalia. Officials fear that Shabab veterans with U.S. passports might try to return to America.

The FBI has not verified “one way or the other” whether any Americans took part in the attack, Holder said. “That is one of the things that we are trying to do with our Kenyan colleagues, to go through the forensic things, materials that we have, physical things, to make that kind of determination.”


Kenyan authorities initially said two or three Americans were among the 10 to 15 terrorists who executed people in the upscale mall, using automatic weapons. Holder said the Kenyan officials had not provided any details of Americans’ involvement to U.S. officials in Nairobi.

He said FBI agents had been “on the ground since right after the incident began” Sept. 21 and have been “flowing … into Nairobi on a continuing basis.” He said he received briefings on the investigation at least once a day, and had briefed the White House.


FBI officials in New York and Washington said they had sent “evidence response teams” to comb through the rubble and to help Kenyan authorities determine who carried out the attack and how. They also will look for intelligence that can help U.S. authorities prevent a similar attack in this country.

The teams include firearms and explosives technicians, DNA experts and agents who can help identify the dead, both assailants and victims. Some are computer experts who hope to unearth any electronic messages and other communications between the attackers and fellow plotters. Others will assist in interviews and conduct their own.


There are signs that some of the gunmen may have worked in the mall, and may have stashed weapons there before the assault, as well as fresh clothing to help them don disguises and escape in the confusion.

Another FBI official, also speaking anonymously, said Kenyan authorities had granted FBI agents broad access to the site. That cooperation wasn’t ensured because Kenya’s president, Uhuru Kenyatta, has been indicted on charges of crimes against humanity by the International Criminal Court, and U.S. relations with Kenya are tense.


Kenya’s interior minister, Joseph Ole Lenku, told reporters that Israel, Britain, Germany, Canada and Interpol also were helping with the investigation. The mall was popular with Nairobi’s large expatriate community.

Several Americans were injured in the attack, but none are known to have been killed. The victims included French, British, Canadian, Chinese, Indian and other non-Kenyan citizens. It’s unclear whether they were residents in Nairobi or foreign tourists.


Some grieving Kenyan families held funerals Thursday, while others continued to search for missing loved ones on the second of three days of national mourning.

Forensic investigators continued the painstaking search for remains at the mall, where three stories collapsed in one area. The Kenya Red Cross reported that 61 people remained missing.


The Shabab’s media office issued a series of taunting messages on Twitter on Thursday.

“The mesmeric performance by the #Westgate Warriors was undoubtedly gripping, but despair not folks, that was just the premiere of Act 1,” one tweet said.


“Kenyans, it’s a great pleasure to have had you completely enthralled for more than 100 hours. What a wonderful audience you’ve been!” said another.

Kenyan authorities also blamed the Shabab for two additional attacks, both in northern Kenya.


Two police officers were killed when their camp was attacked early Thursday in the town of Mandera, near the Somali border, police and Interior Ministry officials said. On Wednesday, militants attacked a police patrol in the town of Wajir, also near the border, killing a civilian bystander.

richard.serrano@latimes.com


kejn.dilanian@latimes.com

Times staff writer Robyn Dixon in Johannesburg, South Africa, contributed to this report.