Kenyan and foreign forensics teams are searching the Westgate shopping complex in Nairobi amid uncertainty over how many bodies they may find following the four-day siege by Islamist militants.
Sixty-seven people are so far known to have died.
Kenya's interior minister has said he does not expect the toll to rise significantly, and believes only the bodies of militants will be found.
But Kenya's Red Cross has said 61 people remain unaccounted for.
Meanwhile Kenya is continuing three days of official mourning for both the civilian and military victims of the siege.
The funeral of pregnant television and radio star Ruhila Adatia-Sood was one of many being held on Thursday.
Flags are flying at half mast amid visibly tighter security around the Kenyan capital. Security guards were scanning passengers with metal detectors before they boarded buses.
Amid rising concern among Kenyans over the authorities' preparedness for such an attack, reports are emerging that the country's counter-terrorism strategy and its disaster response coordination will now be reviewed.
Kenyan investigators have been joined by experts from the US, UK, Germany, Canada and Interpol to comb the sprawling shopping complex for DNA, fingerprints and ballistic clues.
"We have moved to the next phase," Interior Minister Joseph Ole Lenku told a news briefing on Wednesday, saying that he expected the forensic audit to take at least seven days.
He confirmed that five militants were dead and said he expected "insignificant numbers of bodies" would be found amid the rubble after three floors of the building collapsed.
But this runs contrary to the Kenyan Red Cross which says that currently 61 people are missing.
The BBC's Bashkas Jugsodaay says that in Uhuru Park, in central Nairobi, many organisations have set up tents for counselling and taking blood donations, including the Red Cross which has a centre for those looking for missing relatives.
Our reporter says he was there for several hours on Thursday, but did not find anyone looking for a missing person.
Most have already registered the names and left phone numbers to be contacted if there is any news, he says.
The Red Cross said its tracing services closed 15 files on Wednesday; six missing persons were found and re-united with families, and nine bodies were positively identified by their close families, it said.
On Thursday the UK Foreign Office said that the number of British nationals known to have been killed in the attack was lower than previously thought. It had reported that six Britons were among those killed, but it now says that one of the dead previously thought to be British is in fact a Kenyan national.
But at the same time the Foreign Office has warned that the number of British dead could rise before the search of the shopping centre is over.
Work meanwhile is continuing to establish the identities of the deceased militants, and whether one was a woman.
But Mr Lenku urged reporters to "allow the forensic experts to determine whether that is true".
He said he was unable to confirm whether any Britons or Americans were involved, but said that 10 people were being held in connection with the attack.
Somali Islamist group al-Shabab has said it had carried out the attack in retaliation for Kenyan army operations in Somalia.
The militants stormed the Westgate centre on Saturday, throwing grenades and firing indiscriminately at shoppers and staff.
Twitter posts on an al-Shabab account said the group's militants had held 137 people hostage, and claimed the hostages had died after security forces fired chemical agents to end the siege.
The posts could not be verified. A government spokesman denied any chemical agents were used, and authorities called on Kenyans to ignore militant propaganda.
Al-Shabab, which is linked to al-Qaeda, has repeatedly threatened attacks on Kenyan soil if Nairobi did not pull its troops out of Somalia.
About 4,000 Kenyan troops have been serving in the south of Somalia since October 2011 as part of an African Union force supporting Somali government forces.
Scores of people have been killed in Kenya since the incursion in a string of bomb and grenade attacks blamed on - and some claimed by - al-Shabab.
The group is banned as a terrorist group by both the US and the UK and is believed to have between 7,000 and 9,000 fighters.
Its members are fighting to create an Islamic state in Somalia.