The North Korean leader's official wife is Kim Young Sook, the mother of Mr Kim's only daughter, Kim Sul Song. Kim Jong-nam spent part of his childhood in Geneva and Moscow, and is thought to be a computer expert. He is reported to have travelled to Japan twice last year. But correspondents say North Korea's diplomatic isolation would make it difficult for Kim Jong-nam to enter the country under his own identity. Pyongyang only has diplomatic relations with a handful of Western countries, so North Koreans may have little option but to use forged passports and make their journeys clandestinely.
Experts say that North Korea is a known source of forged passports and counterfeit dollars.