SEOUL • Mr Kim Jong Nam had pleaded for his life after an assassination attempt in 2012, South Korean lawmakers said yesterday following a briefing by the spy agency.
The closed-door briefing was conducted by National Intelligence Service chief Lee Byung Ho.
Although the eldest son of former leader Kim Jong Il kept his distance from domestic politics, the North tried to assassinate him in 2012, they said.
"There was one bid in 2012, and Jong Nam in April 2012 sent a letter to Jong Un saying, 'Please spare me and my family,' " Mr Kim Byung Kee, a member of the parliamentary intelligence committee, told reporters.
"It also said, 'We have nowhere to go... we know that the only way to escape is suicide,' " he added.
The spy agency said the killing of Mr Kim Jong Nam had been a "standing order" for North Korean agents since 2012, when he reportedly wanted to seek asylum in the South.
His death echoed the fate of his uncle Jang Song Thaek, who was executed in Pyongyang in December 2013 over charges that included treason and bribery.
The portly and easy-going Kim Jong Nam was believed to be close to his uncle, who was at one time North Korea's second-most po- werful man. An advocate of economic reforms, Mr Jang was known to be close to China.
Mr Kim Jong Nam and Mr Kim Jong Un are sons of Mr Kim Jong Il, who died in late 2011, but they had different mothers.
Mr Kim Jong Nam, the eldest of three sons, lived in exile and had not set foot in North Korea for years. He did not even attend his father's funeral.
He reportedly survived a few assassination attempts. In 2011, a North Korean agent tried to assassinate him in Macau, but failed after a bloody shoot-out with his bodyguards.
That prompted him to leave Macau and move to South-east Asia, reported Chosun Ilbo.
Mr Kim Jong Un, according to Asahi Shimbun, was also suspicious of his blood brother Kim Jong Chol, forcing the latter to pen a letter pledging his loyalty to the regime.
Mr Kim Jong Chol remains confined to a Pyongyang hotel, said the newspaper yesterday.
An aunt and uncle of Mr Kim Jong Un left for the US in 1998 and now live a normal existence as owners of a New York dry-cleaning business.
Others were less fortunate.
Mr Yi Han Yong, a nephew of Mr Kim Jong Nam's mother Sung Hye Rim, publicly criticised the ruling Kim family in his memoir and numerous media interviews after defecting to Seoul in 1982.
He was shot dead outside his home in 1997 in what Seoul's spy agency described as an assassination by North Korean agents. Mr Yi reportedly muttered "spies" before dying. His attackers were never found.