Police suspect that Michiko Akagi, the sister of a Red Army Faction hijacker, is linked to the July 1983 abduction of Keiko Arimoto in Copenhagen after they learned Akagi mailed a letter to her family in Japan from the Danish capital at the same time Arimoto went missing.
The police are expected to question Akagi, who was arrested Tuesday on suspicion of violating the passport law when she arrived at Narita airport, as they believe she knows the details of Arimoto's abduction to North Korea, sources close to the case said.
Red Army Faction members are suspected of luring Arimoto to Copenhagen in mid-July 1983, when she was a 23-year-old college student in London. In September, Pyongyang claimed Arimoto had died in North Korea at the age of 28. She is believed to have entered the country via Moscow.