A letter from Keiko Arimoto to her parents sent from Copenhagen in 1983 suggests she may have been forced to write it, and it was not posted until after she was abducted to North Korea, police sources said Thursday.

Unlike previous letters, the last letter Arimoto’s parents received at their home in Kobe in October 1983 did not have her contact address or the date when it was written, the sources said.

A former college student from Kobe, Arimoto was studying English in London in 1983 before vanishing at the age of 23, apparently from Copenhagen. North Korea last week admitted abducting her and said she died in the country on Nov. 4, 1988, at the age of 28.

In the letter, Arimoto did not write much about her activities, telling her parents, “I cannot receive letters because I am traveling here and there in Europe.”

The letter also said, “It has become like autumn in Europe.” According to the sources, this is odd because the weather in Copenhagen around that time of year is more like that of midwinter in Japan.

The police sources suspect Arimoto was forced to write the letter by Kimihiro Abe, one of nine Japanese Red Army Faction radicals wanted in the 1970 hijacking of a Japan Airlines jetliner to Pyongyang. Police obtained an arrest warrant Wednesday for the fugitive, who lives in North Korea, in connection with Arimoto’s abduction.

Abe may have forced Arimoto to write the letter to camouflage the abduction, and had it posted from Copenhagen by somebody involved in the plot, they said.

Arimoto was in London from April 1982 to June 1983. Before she disappeared, most of her letters sent from London or places she visited carried dates and contact addresses, the sources said.

In June, she wrote from London that she would return home in August. But her parents received a telegram from Greece later in August, saying, “I found a job. My return will be late.”

The letter from Copenhagen said, “It seems my return to Japan will be a bit late because I still have a job to do.”

It was not until last March that her disappearance was confirmed as an abduction, when Megumi Yao, former wife of one of the nine hijackers, testified in court that she took part, with Abe, in the kidnapping in order to force the victim to marry a Japanese man in North Korea.

Yao said she had met Arimoto in London in May 1983 and took her to Copenhagen in July that year, luring her with a false offer of a part-time job.

Yao said she arranged for Arimoto to meet Abe and North Korean agent Kim Yu Chol, who was posing as a diplomat.

Kim is believed to have spirited Arimoto away to North Korea via Moscow shortly after that.

North Korea told Japan of Arimoto’s death during Prime Minister Junichiro Koizumi’s historic Sept. 17 summit in Pyongyang with North Korean leader Kim Jong Il.