Kenya's Westgate mall attackers spent four month's planning in Nairobi

All four gunmen who attacked Kenya's Westgate mall trained in Somalia before crossing into Kenya four months before the September massacre in which they also died, a Western official said Tuesday.

crowded complex, firing from the hip and hurling grenades at shoppers and staff.

Somalia's Al-Qaeda-linked Shebab claimed the attack, saying it was a warning to Kenya to pull its troops out of southern Somalia, where they are fighting the extremists as part of an African Union force.

Mohammed Abdinur Said and Hassan Abdi Dhuhulow, a 23-year old Somali who spent several years in Norway.

Detectives believe they have identified all four gunmen, but so far only the two names have been released.

All four are understood to have trained together in Somalia

Interpol and the FBI are assisting Kenya in trying to identify four charred bodies recovered from the ruins and suspected to be the gunmen.

Two months since the massacre, detectives continue to piece together funding and support networks for the attack, which was well planned and organised.

Four men, all ethnic Somalis, have also been charged gn

Despite witness reports, there is no evidence of a female attacker. At the time, there was widespread speculation of the involvement of a British woman dubbed the "White Widow", 29-year old Muslim convert Samantha Lewthwaite.

The gunmen coldly executed scores of people, with witnesses recounting how in some cases they called out to those wounded, then finished them off at close range.

But investigators who have seen security camera footage, as well as bodies at the morgue, say there was no evidence to support speculation at the time of the siege that some of the victims were tortured before being killed.