Video of Nairobi Mall Shooting: Surveillance footage of the Kenyan shopping mall attack last month shows militants firing weapons and terrified shoppers running for cover.  LARVIK, Norway â As a boy, the Somali immigrant sold newspapers door to door in this peaceful seaside Norwegian town and told neighbors he was going to be a doctor and help people in Africa.  In high school, he began taking a prayer rug to school, but in a community with many Somalis â not to mention Muslims from Libya, Chechnya and elsewhere â he hardly stood out. He rarely got into even mild trouble.  But with grades that fell short of medical school requirements, the young man, Hassan Abdi Dhuhulow, struggled to find a job after high school and began visiting radical jihadist Web sites. In 2009, he took the first of several long trips back to Somalia.  Norwegian investigators now want to know whether the boy who wanted to be a healer grew up to be a killer. They are questioning relatives and friends of Mr. Dhuhulow, 23, to try to determine whether he was one of the four attackers caught on surveillance cameras during the rampage at the Westgate shopping mall in Nairobi, Kenya, last month, when more than 60 men, women and children were killed.  The investigators suspect he was the killer whom investigators have been referring to as Black Shirt, seen hustling past a jewelry store firing his rifle; stalking a wounded man desperately trying to hide in the grocery store; and limping with a bandage below his left knee, his lower leg soaked in blood.  An official familiar with the investigation in Norway confirmed that the Police Security Service had been keeping track of Mr. Dhuhulow since he was a student at Thor Heyerdahl High School, near where he grew up. NRK, the Norwegian state broadcaster, quoted police sources as saying that he had been in contact with central figures of a Norwegian-based Islamist group, Profetens Ummah, or the Prophetâs Community of Believers.  TV 2 in Norway reported that Mr. Dhuhulow had been active in an online forum linked to the Shabab and posted photographs of âmartyrsâ killed in Bosnia. On one site, TV 2 reported, his profile picture was a suicide bomber.  The local newspaper Ostlands-Posten quoted an unnamed former classmate as saying that in high school Mr. Dhuhulow was looking at âodd Web sites,â including more than one about âliquidatingâ American soldiers. The newspaper reported that several former classmates had recognized his gait and his hand gestures in the video footage.  Mr. Dhuhulowâs sister, speaking on the condition that her name not be given, said in an interview here in Larvik: âItâs still hard to believe. I canât bear the thought of this actually being true. Itâs just too much to come to terms with.â  She said that officers from the Police Security Service had asked her whether her brother had placed calls from the Westgate mall during the siege. She said that he had not and that the family was unaware of any role he might have played.  She said she did not believe her brother could have taken part in the attack on Westgate and could not say she recognized him from the video. âMy mother and father and me, we donât even know if he is dead or alive,â she said.  Although a person of interest in the case, Mr. Dhuhulow may yet prove to have had no connection to the attack.  The Police Security Service said in a statement on Friday that it had ânot yet been determined whether a named Norwegian citizen actually took part in the attack or not.â But the statement added, âBased on the information that we have uncovered this far in the investigation, however, the suspicion of his involvement has been strengthened.â  A man with the same name as Mr. Dhuhulow was arrested in Somalia in connection with the killing of a radio journalist but was freed by a military tribunal for lack of evidence in March.  The devastating siege of Westgate shocked not just Kenya but the entire region, from Ethiopia to Tanzania, prompting worries of more attacks abroad by the Shabab or the groupâs local affiliates. In Ugandaâs capital, Kampala, extra police officers were at checkpoints and guarded shopping malls on Friday after warnings of an attack.  Henrik Pryser Libell reported from Larvik, and Nicholas Kulish from Nairobi, Kenya. Josh Kron contributed reporting from Nairobi.
Investigators are questioning the family and friends of Hassan Abdi Dhuhulow, a Norwegian citizen born in Somalia, whose sister said he began taking âlong vacationsâ there in 2009.