Kenya's security chiefs have been summoned to appear before parliament's defence committee for questioning over the Westgate mall siege.The BBC's David Okwembah says a blame game is playing out in the Kenyan media, with various security agencies pointing the finger at each other.Sixty-seven people are known to have died in the attack, while Kenya's Red Cross says 61 people are still missing.Forensic experts are still combing the complex, looking for bodies and clues.Somali Islamist group al-Shabab says it was behind the attack and subsequent four-day siege at the upmarket mall in the Kenyan capital.Kenya is in its third day of official mourning for both the civilian and military victims of the siege.President Uhuru Kenyatta is attending the funeral of his nephew and his nephew's fiancee at a church service in the capital, Nairobi, where he has addressed the congregation.Mbugua Mwangi and Rosemary Wahito were among those killed in the mall on Saturday.They will later be buried in Ichaweri village in Gatundu about an hour's drive from Nairobi.'Jewellery missing'The summoning of the heads of the various security agencies to appear before the parliamentary defence committee on Monday comes amid rising concern among Kenyans over the authorities' preparedness for such an attack."The time for responsibility and accountability has come," the defence committee's chairman Ndung'u Gethenji is quoted by Kenya's Daily Nation newspaper as saying.Local media have reported that National Intelligence Service boss Michael Gichangi, one of those asked to appear before the committee, passed on intelligence about a possible attack to the police.But the Daily Nation says that a highly placed police source denied that such information was received.Irene Anyango, manager of a Westgate jewellery shop, is one of the few people allowed into the mall following the end of the siege.She said the mall was barely recognisable given the damage."It was a nightmare… and the shop was a totally different place," she told the BBC."So many things were not intact... a lot of things weren't there, a lot jewellery - we're talking about diamonds, necklaces - all the rings."Ms Anyango said 90% of the jewellery was missing from the shop, which is now flooded."As far as we know for the last couple of days they were intact - we don't understand what's happening but they're not there," she said.Many people not only face the trauma of losing family and colleagues but also the possibility of losing their jobs, she added.On Thursday the funeral of pregnant television and radio star Ruhila Adatia-Sood was one of many funerals held.Some 2,500 people packed into the Muslim Ismaili community's sports and social club in Nairobi to pay their respects to her and another woman killed in the siege, the AFP news agency reports.They had been taking part in a children's cooking competition on the rooftop car park, when gunmen stormed the shopping centre."We are a small community. In a tragedy like this we get together," Azym Dossa, who lent his fleet of coaches to ferry mourners across town, told AFP.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 sent to Somalia to help pro-government forces battle 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.