NAIROBI, Kenya — After almost a week, there is no precise death toll, no word on the fate of dozens still missing and no details on the al-Qaida-linked terrorists who attacked Nairobi's most upscale mall.

As al-Shabab militants struck two Kenyan border towns and threatened more violence, relatives of the mall victims wept outside the city morgue Thursday, frustrated by the lack of information and a holdup in the release of bodies of the victims.

Roy Sam, whose brother, 33-year-old Thomas Ogala, was killed, said he had been going to the morgue since Monday, but workers there had not prepared his brother's body, which was mangled by a close-range gunshot wound to the head – an apparent execution.

"They said they were going to prepare the body to make it look nice, but we came back the next day and the next, and it wasn't any different," Sam said.

The morgue superintendent, Sammy Nyongesa Jacob, said workers were told not to touch the bodies until post-mortuary studies had been completed.

Kenya's chief pathologist, Johansen Oduor, said his team was removing bullets and shrapnel from victims to find out exactly how they were killed, then handing them over to police as evidence.

"A lot of them died from bullet wounds – the body, the head, all over," he said. "Some also died from grenades, shrapnel."

He refused to reveal how many bodies were in the morgue but said he was told to expect more – though he would not say how many.

It was the largest terrorist attack in Kenya since the 1998 bombing of the U.S. Embassy, and FBI agents were dispatched to do fingerprint, DNA and ballistic analysis on the bodies. They were joined by investigators from Britain, Germany and Canada.

There have been no details on what the international team has found so far in the bullet-scarred, scorched mall, work that is expected to take at least a week, said Kenyan police spokeswoman Gatiria Mboroki.

The Kenyan Red Cross said Thursday that 61 people remain missing and many worry they may be buried under the rubble – though the government has insisted few victims are believed to still be inside.

The government says at least 67 people were killed in the assault by 12 to 15 al-Shabab militants on the Westgate Mall, including 61 civilians and six security forces. Five militants also were killed, but questions remained about the fate of the remaining attackers and fears persisted that some had managed to escape.

Many also questioned how such an audacious attack could have been carried out at one of Kenya's most prominent sites and a symbol of its economic success, where shops for retail giants like Adidas, Nike and Bose drew both foreigners as well as wealthy Kenyans.

In what appeared to be the first round of political blame-shifting, officials from the National Intelligence Service gave journalists a report from Sept. 21, 2012 – exactly one year before the Saturday attack – that said suspected al-Shabab operatives were in Nairobi and planned to mount suicide attacks on an "undisclosed date, targeting Westgate Mall."

Al-Shabab, meanwhile, threatened more attacks in Kenya, saying Thursday on its Twitter feed that the mall attack "was just the premiere of Act 1."

"Make your choice today and withdraw all your forces," the group's leader, Ahmed Abdi Mohamed Godane, said in a statement posted on the Internet late Wednesday. "Otherwise be prepared for an abundance of blood that will be spilt in your country, economic downfall and displacement."

Al-Shabab said the Nairobi mall attack was not only directed at Kenya, but was also "retribution against the Western states that supported the Kenyan invasion and are spilling the blood of innocent Muslims in order to pave the way for their mineral companies."

The militant group, whose name means "The Youth" in Arabic, first began threatening Kenya with a major terror attack in late 2011, after Kenya sent troops into Somalia following a spate of kidnappings of Westerners inside Kenya.

Kenya has also suffered many small-scale attacks along its 682-kilometer (423-mile) border with Somalia, and the group struck again Wednesday night and early Thursday, targeting two Kenyan towns near the Somali border in strikes that killed three people, including two police officers.

As the investigation continued into the mall attack, FBI agents from New York City, including members of the Joint Terrorism Task Force, bomb squad technicians and evidence recovery specialists arrived in Nairobi, a U.S. law enforcement official confirmed. The official spoke on condition of anonymity because he wasn't authorized to discuss the operation.

The international investigation is being coordinated by Interpol, which sent an incident response team that arrived in Nairobi on Wednesday, the Kenyan government said.

The Interpol team includes disaster victim identification and data specialists who will carry out real-time comparisons of evidence collected inside the mall against the France-based agency's database on DNA and fingerprints from its 190 member country network, said Interpol official Jean-Michel Louboutin.

"Whether it be through comparison of information against Interpol's global databases, or the issuance of a notice to identify a victim, locate a wanted person, or seek additional information about suspects, we will offer all necessary assistance to help bring those responsible to justice," Louboutin said in a statement.

___

Associated Press writers David Rising in Nairobi, Kenya and Tom Hays in New York contributed to this story.

Also on HuffPost:

Loading Slideshow...
  • A plume of black smoke billows over the Westgate Mall, in Nairobi, Kenya Monday, Sept. 23, 2013. Multiple large blasts have rocked the mall where a hostage siege is in its third day. Associated Press reporters on the scene heard multiple blasts and a barrage of gunfire. Security forces have been attempting to rescue an unknown number of hostages inside the mall held by al-Qaida-linked terrorists.(AP Photo/Jonathan Kalan)

  • Armed police from the General Service Unit take cover behind a wall during a bout of gunfire, outside the Westgate Mall in Nairobi, Kenya Monday, Sept. 23, 2013. Hostages being held by al-Qaida-linked terrorists in a Nairobi mall have not been released despite an earlier statement from the military that "most" had been rescued, a person connected to the situation told The Associated Press on Monday. (AP Photo/Ben Curtis)

  • Paramedics and police officers run outside the Westgate Mall in Nairobi after heavy shooting started Monday, Sept. 23, 2013. Kenya's military launched a major operation at the upscale Nairobi mall and said it had rescued "most" of the hostages being held captive by al-Qaida-linked militants during the standoff. (AP Photo/Sayyid Azim)

  • Kenya security forces are seen behind a wall outside the Westgate Mall in Nairobi, Kenya Monday morning, Sept. 23, 2013. Kenya's military launched a major operation at the upscale Nairobi mall and said it had rescued "most" of the hostages being held captive by al-Qaida-linked militants during the standoff that killed at least 68 people and injured 175. (AP Photo/Jerome Delay)

  • Kenya security personnel take cover outside the Westgate Mall after shooting started inside the mall early Monday morning, Sept. 23, 2013. Kenya's military launched a major operation at the upscale Nairobi mall and said it had rescued "most" of the hostages being held captive by al-Qaida-linked militants during the standoff that killed at least 68 people and injured 175. (AP Photo/Sayyid Azim)

  • Kenya security forces are seen behind a wall outside the Westgate Mall in Nairobi, Kenya Monday morning, Sept. 23, 2013. Kenya's military launched a major operation at the upscale Nairobi mall and said it had rescued "most" of the hostages being held captive by al-Qaida-linked militants during the standoff that killed at least 68 people and injured 175. (AP Photo/Jerome Delay)

  • Kenya security forces are seen behind a wall outside the Westgate Mall in Nairobi, Kenya Monday morning, Sept. 23, 2013. Kenya's military launched a major operation at the upscale Nairobi mall and said it had rescued "most" of the hostages being held captive by al-Qaida-linked militants during the standoff that killed at least 68 people and injured 175. (AP Photo/Jerome Delay)

  • Onlookers gather on a hill to observe the Westgate Mall after a bout of heavy gunfire just after dawn in Nairobi, Kenya Monday, Sept. 23, 2013. Helicopters circling overhead, Kenya's military launched a major operation Sunday night at the upscale Nairobi mall and claimed it had rescued "most" of the hostages being held captive by al-Qaida-linked militants during a standoff that killed at least 68 people and injured 175. (AP Photo/Ben Curtis)

  • Relatives wait at the Nairobi City Mortuary following the mall attack in Kenya, Sunday, Sept. 22, 2013. Kenyan authorities said Islamic extremist attackers remain inside the upscale Kenyan shopping mall, holding an unknown number of hostages, after killing at least 39 and injuring 150 during Saturday's attack. (AP Photo/Khalil Senosi)

  • Groups of onlookers gather on a road looking down over the Westgate Mall in Nairobi, Kenya Sunday, Sept. 22, 2013. Multiple barrages of gunfire erupted Sunday morning from the upscale Kenyan mall where there is a hostage standoff with Islamic extremists nearly 24 hours after they attacked using grenades and assault rifles. (AP Photo/Ben Curtis)

  • A line of soldiers from the Kenya Defense Forces run in front of the Westgate Mall in Nairobi, Kenya Sunday, Sept. 22, 2013. Multiple barrages of gunfire erupted Sunday morning from the upscale Kenyan mall where there is a hostage standoff with Islamic extremists nearly 24 hours after they attacked using grenades and assault rifles. (AP Photo/Ben Curtis)

  • Soldiers from the Kenya Defense Forces carry a wounded colleague, following the sound of explosions and gunfire, out of the Westgate Mall in Nairobi, Kenya Sunday, Sept. 22, 2013. Associated Press journalists at the scene of a hostage standoff said a barrage of gunfire erupted from the upscale Kenyan mall Sunday morning and moments later two wounded Kenyan security forces were carried out of the mall. (AP Photo/Ben Curtis)

  • Trucks of soldiers from the Kenya Defense Forces arrive after dawn outside the Westgate Mall in Nairobi, Kenya Sunday, Sept. 22, 2013. Islamic extremist gunmen lobbed grenades and fired assault rifles inside Nairobi's top mall Saturday, killing dozens and wounding over a hundred in the attack. Early Sunday morning, 12 hours after the attack began, gunmen remained holed up inside the mall with an unknown number of hostages. (AP Photo/Ben Curtis)

  • Trucks of soldiers from the Kenya Defense Forces arrive after dawn outside the Westgate Mall in Nairobi, Kenya Sunday, Sept. 22, 2013. Islamic extremist gunmen lobbed grenades and fired assault rifles inside Nairobi's top mall Saturday, killing dozens and wounding over a hundred in the attack. Early Sunday morning, 12 hours after the attack began, gunmen remained holed up inside the mall with an unknown number of hostages. (AP Photo/Ben Curtis)

  • Armed special force aim their guns at the Westgate Mall in Nairobi, Kenya on Saturday, Sept. 21 2013, after gunmen threw grenades and opened fire during an attack that left multiple dead and dozens wounded. A witness to the attacks on the upscale shopping mall says that gunmen told Muslims to stand up and leave and that non-Muslims would be targeted(AP Photo/Khalil Senosi)

  • Civilians who had been hiding inside during the gun battle manage to flee from the Westgate Mall in Nairobi, Kenya Saturday, Sept. 21, 2013. Gunmen threw grenades and opened fire Saturday, killing at least 22 people in an attack targeting non-Muslims at an upscale mall in Kenya's capital that was hosting a children's day event, a Red Cross official and witnesses said. (AP Photo/Jonathan Kalan)

  • A body is seen on the floor, below right, as smoke fills the air inside the Westgate Mall in Nairobi, Kenya Saturday, Sept. 21, 2013. Gunmen threw grenades and opened fire Saturday, killing at least 22 people in an attack targeting non-Muslims at an upscale mall in Kenya's capital that was hosting a children's day event, a Red Cross official and witnesses said. (AP Photo/Jonathan Kalan)

  • A woman who had been hiding during the gun battle runs for cover after armed police, seen behind, enter the Westgate Mall in Nairobi, Kenya, Saturday, Sept. 21, 2013. Gunmen threw grenades and opened fire Saturday, killing at least 22 people in an attack targeting non-Muslims at an upscale mall in Kenya's capital that was hosting a children's day event, a Red Cross official and witnesses said. (AP Photo/Jonathan Kalan)

  • An armed police officer takes cover during a bout of gunfire outside the Westgate Mall in Nairobi, Kenya Saturday, Sept. 21, 2013. Gunmen threw grenades and opened fire Saturday killing at least 22 people in an attack targeting non-Muslims at an upscale mall in Kenya's capital that was hosting a children's day event, a Red Cross official and witnesses said. (AP Photo/Ben Curtis)

  • People run from the Westgate Mall in Nairobi, Kenya.

    Gunmen threw grenades and opened fire during an attack that left multiple dead and dozens wounded. A witness to the attacks on the upscale shopping mall says that gunmen told Muslims to stand up and leave and that non-Muslims would be targeted.

  • A woman who had been held hostage reacts after being released.

    Suspected terrorists engaged Kenyan security forces in a drawn out gun fight at the Westgate Mall in Nairboi.

  • Woman runs for cover.

    A woman who had been hiding during the gun battle runs for cover after armed police, seen behind, enter the Westgate Mall in Nairobi, Kenya, Saturday, Sept. 21, 2013.

  • Location of the attack.

    Graphic shows detail of shopping mall site of fatal gun attack in Nairobi, Kenya.

  • View inside the mall.

    Armed police take cover behind escalators as smoke fills the air inside the Westgate Mall in Nairobi, Kenya Saturday, Sept. 21, 2013.

  • Raw: Gunmen Attack Shopping Mall in Kenya

    Gunmen threw grenades and opened fire at an upscale mall in Kenya's capital on Saturday, killing at least 10 people.

  • Armed police on scene.

    Armed police leave after entering the Westgate Mall in Nairobi, Kenya Saturday, Sept. 21, 2013.

  • Mall-goers flee after attack.

    Civilians who had been hiding inside during the gun battle manage to flee from the Westgate Mall in Nairobi, Kenya Saturday, Sept. 21, 2013.

  • An armed police officer takes cover during a bout of gunfire outside the Westgate Mall.

    The mall in Kenya's capital was hosting a children's day event at the time of the attack, a Red Cross official and witnesses said.

  • Armed police at the Westgate Mall.

    Armed police crouch down and take position during a gun battle outside the Westgate Mall in Nairobi, Kenya Saturday, Sept. 21, 2013.

  • Civilians leave the mall after gun battle.

    Civilians who had been hiding during the gun battle hold their hands in the air as a precautionary measure before being searched by armed police leading them to safety, inside the Westgate Mall in Nairobi, Kenya Saturday, Sept. 21, 2013.

  • A rescue worker helps a child outside the Westgate Mall.

  • Security helps a woman outside the Westgate Mall in Nairobi, Kenya Saturday, Sept. 21, 2013, after gunmen threw grenades and opened fire during an attack that left multiple dead and dozens wounded.

  • People flee the scene of the attack.

    Security helps people outside the Westgate Mall in Nairobi, Kenya Saturday, Sept. 21, 2013, after gunmen threw grenades and opened fire during an attack that left multiple dead and dozens wounded.

  • A wounded man is escorted away from the mall.

    Witnesses say a half dozen grenades also went off along with volleys of gunfire in and around the mall.

  • A rescued hostage collapses on the ground after being freed by police at Westgate Mall.

    A witness to the attacks on the upscale shopping mall says that gunmen told Muslims to stand up and leave and that non-Muslims would be targeted.

  • Two women hug outside the mall after the attack.

    Bursts of gunfire were heard from outside the Westgate Mall Saturday, where cars were left abandoned. Witnesses say a half dozen grenades also went off along with lobbies of gunfire that started at midday.

  • Woman escapes from the Westgate Mall.

    A woman who had been hiding inside and managed to flee, sits in a state of shock, as an unidentified armed member of the security forces, above, keeps watch outside the Westgate Mall in Nairobi, Kenya Saturday, Sept. 21, 2013.

  • Security officers keep a crowd under control outside the Westgate Mall

  • An injured person makes a phone call as he is helped on his arrival at the Aga Khan Hospital after the attack at the Westgate Mall.

  • An injured person arrives at the hospital after the attack on the Westgate Mall.

  • A injured child is wheeled away on a shopping trolley outside the Westgate Mall.

  • A security officer helps a wounded woman outside the Westgate Mall in Nairobi, Kenya Saturday, Sept. 21, 2013, after gunmen threw grenades and opened fire during an attack that left multiple dead and dozens wounded. A witness to the attacks on the upscale shopping mall says that gunmen told Muslims to stand up and leave and that non-Muslims would be targeted. (AP Photo/Khalil Senosi)

  • An injured man arrives at the Aga Khan Hospital in Nairobi after the attack at the Westgate Mall.

  • An injured man arrives at the Aga Khan Hospital after the attack at the Westgate Mall.

    A witness to the attacks says that gunmen told Muslims to stand up and leave and that non-Muslims would be targeted. Initial police reports had described the incident as a botched robbery. Witnesses say a half dozen grenades also went off along with volleys of gunfire in and around the mall.

  • A security guard helps a child outside the Westgate Mall.

    A witness to the attacks on the upscale shopping mall says that gunmen told Muslims to stand up and leave and that non-Muslims would be targeted.