Five years ago, Kim Jong-nam, the half-brother of North Korea's ruler, pleaded with his younger sibling to spare his life, according to two lawmakers in South Korea.

He wrote a letter to Kim Jong-un, who took power after their father Kim Jong-il died in December 2011, and asked him to withdraw a standing order for his assassination, according to the lawmakers, who were briefed by South Korea's spy agency.

"We have nowhere to go, nowhere to hide. We are well aware that the only way to escape is suicide," Kim Jong-nam said in a letter to Kim Jong-un, one of the lawmakers said.

Kim Jong-nam, 46, died after an assault, possibly with poison, at the low-cost airport terminal at KLIA on Monday. US and South Korean government officials have said they believe he was assassinated by agents from the North.

The eldest son of Kim Jong-il, Kim Jong-nam was hidden from public view for years because his father and actress mother were not legally married. He was not shown to his grandfather, North Korea's founding President Kim Il-sung, until he was five years old.

Kim Jong-nam spent nine years at an international school in Geneva.

When he returned to Pyongyang, he joined the government. His father became leader in 1994 and Kim Jong-nam was expected by some eventually to succeed him - until the Disneyland incident.

In May 2001, Kim Jong-nam was nabbed at Tokyo's Narita airport and held for using a false Dominican Republic passport. He was accompanied by his wife, another woman believed to be a nanny, and a four-year-old boy, his son, according to media reports.

He said the family wanted to visit Tokyo Disneyland. All four were deported and went back to North Korea via Beijing.

His father was embarrassed and after that, Kim Jong-nam's star was on the wane.

Kim Jong-nam's mother Song Hye-rim ended up living in Moscow, away from him, and died there after struggling with depression for years. Kim said he often visited the mother's grave in Moscow.

Loved being free

After the Disneyland incident, much of the rest of Kim Jong-nam's life was spent overseas, first in China and then in Macau.

South Korea's intelligence service said he had wives and children both in Beijing and Macau, according to lawmakers.

"Because I was educated in the West, I was able to enjoy freedom from early age and I still love being free," he said in notes to a Japanese journalist, Yoji Gomi, who wrote a book on Kim Jong-nam in 2012. "The reason I visit Macau so often is because it's the most free and liberal place near China, where my family lives.

South Korean lawmakers said the spy agency told them that young, unpredictable Kim Jong-un had issued a "standing order" for his half-brother's assassination after he took power, and that there had been a failed attempt in 2012.

"Kim Jong-un said: 'I just hate him. So get rid of him,'" Kim Byung-kee, one of the lawmakers, cited the spy agency as saying about the standing order.

Some analysts have said Jong-un believed his brother could be used in any overthrow of his regime.

After that, Kim Jong-nam did not stay long in any place, and travelled frequently between various cities in South-East Asia and China.

Kim Jong-nam had not kept his disdain for his brother a secret.

"I'm his half-brother, but I've never met him so I don't know," he said in another note to Gomi.

"I'm concerned how Jong-un, who merely resembles my grandfather, will be able to satisfy the needs of North Koreans. Kim Jong-un is still just a nominal figure and the members of the power elite will be the ones in actual power. The dynastic succession is a joke to the outside world."

He added: "The Kim Jong-un regime will not last long. Without reforms, North Korea will collapse, and when such changes take place, the regime will collapse."

Numerous North Korean officials have been purged or killed since Kim Jong-un came to power. Those include his uncle, Jang Song-thaek, who was considered the country's second most-powerful person and was believed to have been close to Kim Jong-nam, who he had helped raise.

"I was raised getting special love from the aunt and uncle and I am not denying that they are even now taking special care of me," Kim Jong-nam said in a note written to Gomi before his uncle was killed.

- Reuters