The man being investigated by Norwegian police over the attack on Kenya's Westgate shopping centre is Hassan Abdi Dhuhulow, BBC Newsnight has learned.
Phone calls home
One relative, who spoke to our correspondent on condition of anonymity, said that Dhuhulow left for Somalia in 2009. He made infrequent, increasingly erratic, phone calls to the family, they said, the last one coming in the summer when he said that he was in trouble and wanted to return home.
On being shown the CCTV footage of the Kenya attackers by Newsnight, Dhuhulow's relative said: "I don't know what I feel or think... If it is him, he must have been brainwashed."
Reporting for Newsnight, Gabriel Gatehouse travelled to the coastal town of Larvik, 120 km (75 miles) south of Oslo, where Dhuhulow's family made their home.Morten Henriksen, one of the family's former neighbours, has not seen Dhuhulow for years. "He was pretty extreme, didn't like life in Norway… got into trouble, fights, his father was worried," Mr Henriksen said of Dhuhulow as a teenager.
When shown the CCTV footage of the four Kenya attackers he said that the one dressed in a black shirt or jacket could be Dhuhulow.
'Falling between cultures'