LARVIK, Norway — The trail in the investigation into the deadly attack on a Kenyan shopping mall leads all the way to Scandinavia, where the Norwegian police have identified a man who may have been among the assailants.

Investigators are questioning relatives and friends of Hassan Abdi Dhuhulow, 23, a Norwegian citizen born in Somalia, to try to determine whether he was one of the four militants captured on surveillance footage inside the shopping mall, calmly killing shoppers on a Saturday afternoon last month.

His sister, who spoke on the condition of anonymity, said in an interview here in Larvik, where Dhuhulow grew up, that officers from the Norwegian security police had asked her whether her brother had placed calls from Nairobi, including from the Westgate shopping mall, during the siege. She said that he had not and that the family was unaware of any role he might have played in the attack.

“My mother and father and me, we don’t even know if he is dead or alive,” she said. “We are waiting for the whole issue to become clearer.”

A spokesman for the Norwegian Police Security Service, Martin Bernsen, said investigators were also unsure whether Dhuhulow was still alive. Several explosions and a fire at the mall have made it hard to distinguish between the remains of the victims and attackers. Authorities have been unable thus far to identify any of the militants among the bodies pulled from the rubble.

Johansen Oduor, chief government pathologist, said that remains believed to belong to three of the attackers had been pulled from the rubble on Thursday and taken to the Nairobi City Mortuary, but that identification would likely require advanced forensics including DNA testing.

“The bodies are charred. There’s no face. There’s no clothes,” Oduor said. “There are body parts and with body parts it’s difficult to tell” even how many of the attackers there were.

The remains were recovered next to AK-47 rifles, the same kind of firearms the attackers were carrying in footage from security cameras in the mall. Kenyan security forces do not use that make of rifle.

“If you are found next to an AK, most likely you are one of the attackers,” Oduor said.

A man with the same name as Dhuhulow was arrested in Somalia in connection with the murder of a radio journalist but was freed by a military tribunal for lack of evidence in March.

In 2009, Dhuhulow began going on what his sister called “long vacations” to Somalia. Contact with the family was sporadic, and she could not remember whether she had last spoken to him last year or the year before.

“My brother leads a different life than me,” she said.

Norway has increasingly come into focus as investigators from Kenya, the United States, Norway and elsewhere work to piece together the al-Shabab’s international network. Navy SEALs staged an unsuccessful raid in the Somali coastal town of Baraawe this month to try to capture an al-Shabab mastermind, Abdikadir Mohamed Abdikadir, also known as Ikrima. Abdikadir is believed to have lived in Norway as an asylum seeker between 2004 and 2008.