japanese count down is start

Jordan is being pushed to meet ISIS' demand before the sun sets Thursday over Mosul, Iraq, according to a new message purportedly from the terror organization.

Authorities are to bring convicted terrorist Sajida al-Rishawi to the Turkish border by 5:30 p.m. Mosul time (9:30 a.m. ET), or Jordanian ISIS hostage Moaz al-Kassasbeh will be executed "immediately."

Jordan has said it's willing to swap al-Rishawi for the Jordanian pilot.

But could releasing al-Rishawi lead to the sparing of his life and that of another hostage, Japanese journalist Kenji Goto?

CNN could not independently confirm the authenticity of the latest message, which was read by a person claiming to be Goto and posted online by ISIS supporters. In the message, Goto purportedly calls for al-Rishawi's release in "exchange for my life."

Goto, 47, is reported to have three children, two of them with his current wife.

His mother begged Japanese Prime Minister Shinzo Abe to secure her son's release.

"Please save the life of Kenji," Junko Ishido said. "I call on you to work with all your strength in negotiations with the Jordanian government, until the very end."

Al-Kassasbeh's father has called on Jordanian authorities to act as well.

"I firmly ask whomever has sent Moaz to fight outside the borders of Jordan, on a mission unrelated to us, to make strong efforts to bring back Moaz," Safi al-Kassasbeh said Tuesday.

ISIS says it captured al-Kassasbeh after he ejected from his F-16 jet last month near Raqqa, the militant group's de facto capital in Syria.

Jordan rallies around captured pilot 02:23

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The pilot's father suggested his son's case shouldn't be mixed up with Goto's.

To link Moaz's situation with the Japanese journalist, this has nothing to do with us," he said. "The Japanese journalist has his country to defend him."

Grim track record

ISIS, which holds large areas of Iraq and Syria under its brutal rule, has a grim track record of ruthlessly killing hostages. Last year, it publicized its series of beheadings of three American and two British captives.

The group has made a series of demands regarding the Jordanian and Japanese hostages.

A post from the group on Tuesday announced that time was suddenly in short supply for Goto and the Jordanian pilot.

ISIS demands hostage swap 02:02

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CNN couldn't independently verify the authenticity of the messages. The Japanese government said there was no evidence so far that it wasn't Goto who has been speaking in them.