The woman, Siti Aishah, was detained over the Cold War-style killing of Kim Jong-Nam in a Malaysian airport on Monday that South Korea says was carried out by female agents armed with poison working for Pyongyang.
Indonesian Vice President Jusuf Kalla suggested that the 25-year-old Aishah, was a "victim" of a "scam" who thought she was taking part in a reality show involving hidden cameras.
Malaysian police say that Jong-Nam, the estranged elder brother of Kim Jong-Un, was preparing to board a plane to Macau when he was jumped by two women who squirted some kind of liquid in his face.
Authorities initially arrested a 28-year-old woman carrying a Vietnamese passport and later arrested a 26-year-old Malaysian man, who led them to his girlfriend, Aishah.
In the Jakarta neighbourhood of Tambora, where Aishah used to live with her then husband, her former father-in-law was horrified on hearing the news of her arrest over the dramatic murder.
"I was shocked -- no way," said Tija Liang Kiong, 56. "There's no way such a nice person would do that. I could not believe it because she was a good person."
"She was kind -- if she was not kind I would not marry her off to my son," he added.
She married the son after meeting him while working for Kiong's business.
They had a baby and went to Malaysia to find work but got a divorce in 2012, Kiong said.
Kiong said the child they had still lives with his family and that Aishah last visited her son on January 28. Indonesian immigration authorities said she flew to Malaysia from Indonesia on February 2.
One of her former neighbours, 25-year-old Nihayah, also expressed surprise at the news.
"I was very shocked because she was very normal, I could not believe it at all," the neighbour, who like many Indonesians goes by one name, told AFP.
"The family was nice and friendly, but she (Siti) was quiet. She only answered when asked. She was quiet and polite."
Meanwhile vice president Kalla said that from the information they had received it appeared Aishah was the "victim of a scam or a fraud".
"If she really was an agent I believe she would not have been found," he said.
Kalla said he thought she was tricked into believing that "she was playing a game" and taking part in a "reality show" that involved hidden cameras, and added the Indonesian embassy in Kuala Lumpur would support her.
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