But it hasn’t been confirmed:

A purported Taliban spokesman claimed the hardline militia killed a second South Korean hostage Monday because the Afghan government failed to release imprisoned insurgents. Afghan officials said they hadn’t recovered a body and couldn’t confirm the claim.
The Al-Jazeera television network, meanwhile, showed footage that it said was seven female hostages in Afghanistan.

Militant spokesman Qari Yousef Ahmadi said senior Taliban leaders decided to kill the male captive because the government had not met Taliban demands to trade prisoners for the Christian volunteers.
“The Kabul and Korean governments are lying and cheating. They did not meet their promise of releasing Taliban prisoners,” Ahmadi, who claims to speak for the Taliban, said by phone from an undisclosed location. “The Taliban warns the government if the Afghan government won’t release Taliban prisoners then at any time the Taliban could kill another Korean hostage.”
Ghazni Gov. Marajudin Pathan said officials were aware of the Taliban’s claim but hadn’t recovered a body. He said police were looking but he couldn’t say when they might find anything.