SEOUL - The whereabouts and safety of the 21-year -old son of Kim Jong Nam is one of the many questions that arose following the death of his father earlier this week.

Born in Pyongyang in 1995, Kim Han Sol moved to Macau at a young age after his father reportedly fell out of favour with grandfather Kim Jong Il in the early 2000s.

In a rare TV interview with Finnish broadcaster YLE in 2012, he openly spoke of his wish for eventual reunification of the Korean peninsula.

"I have always dreamed one day I will go back and make things better, make it easier for all the people there," he told the interviewer, former UN Under Secretary-General Elisabeth Rehn.

Sporting black framed glasses and two earrings in his left ear, he appeared confident and articulate in the interview.

"I also dream of reunification because it's really sad that I can't go to the other side (South Korea) and see my friends there."

According to the YLE website, Kim Han Sol had never met his grandfather Kim Jong Il, who led the autocratic state until his death in December 2011. His uncle Kim Jong Un formally took power the following year.

Asked why his uncle was appointed as leader, the then 17-year-old replied: "My dad was definitely not really interested in politics. I really don't know how he (Kim Jong Un) became a dictator ... It was between him and my grandfather."

Kim Jong Nam, 45, died after he was allegedly killed by two women believed to be North Korean agents at Kuala Lumpur International Airport on Monday.

Commenting on the case, Dr Jae H. Ku, director of the US-Korea Institute at the Johns Hopkins School of Advanced International Studies told New York Times: "Maybe Kim Jong Nam was about to do something drastic that would either compromise the regime or the family. By the nature of things in North Korea, the fact that he is in the bloodline represented a threat."

The young Kim said during the 2012 interview he wasn't aware of his family's status in North Korea until he was much older.

"I really didn't know until later on that my grandfather was a leader in Korea... Little by little, through conversations my parents had, I started to put the puzzle pieces together and then I realised who he was."

According to South Korea's spy agency, Kim Jong Nam's family members enjoyed Beijing's protection. Kim Han Sol is the son of Kim Jong Nam's second wife Lee Hye Kyong. His family lived in virtual exile in the Chinese territory of Macau, while his father's first wife and son lived in Beijing.

He is now believed to be holed up in Macau with his family, according to Seoul lawmaker Lee Cheol Woo, a member of South Korea's parliamentary intelligence committee who was briefed by the South's spy chief. "They are under the protection of the Chinese authorities," Lee was quoted saying by AFP.

Kim Han Sol in the interview described an isolated childhood where the family had to keep a very low profile. "All my friends are from outside, like Macau," he said.

In 2011, the United World College (UWC) in the war-torn town of Mostar extended a scholarship to Kim Han Sol after Hong Kong refused him a visa to study there. The school is one of 17 UWC schools worldwide that aim to bring together students from conflict zones with the goal of healing ethnic divisions after the Bosnian war of the 1990s.

Kim Han Sol said he enjoyed his friendships with Americans and South Koreans while at school, despite the tensions between his country and theirs.

While it was awkward when he first met his South Korean friends, "little by little we started to understand each other ... and sometimes we share stories from back home and realise how similar we are: the same language, the same culture - it really is just political issues that divide the nation in half," he said in comments reported by The Guardian newspaper.

He also revealed he has a Libyan roommate who would share stories of the 2011 revolution in Libya which overthrew the four-decade rule of dictator Muammar Gaddafi.

Kim Han Sol, according to media reports, has graduated from France's prestigious Sciences-Po university. Kim Han Sol has been admitted to a graduate school of Oxford University. But he has not yet enrolled, reported the Dong-A Ilbo newspaper.

A family friend told Chosun Ilbo which visited the family's home in Macau: "I tried to call Jong Nam's wife after learning about his assassination on the news last night, but her mobile phone was turned off.

"They probably had an action plan in case something bad happened to him."