Two North Koreans are in custody in South Korea after being accused of posing as refugees and plotting to kill Hwang Jang-yop, the highest ranking North Korean official ever to defect to Seoul.
Hwang once mentored leader Kim Jong Il, but defected to the south in 1997. South Korean media reports that Hwang worked as Kim's private tutor on his "juche" philosophy of self reliance.
The two Army Majs. Kim Myong Ho and Dong Myong Kwan confessed to investigators that they were ordered to report back on Hwang's activities and to prepare to "slit the betrayer's throat," a senior prosecutor said.
"One of the suspects attempted suicide during questioning, but wasn't seriously hurt," prosecution spokesman Oh Se-in said.
The arrest of the alleged spies follows tensions that have escalated after a South Korean warship mysteriously exploded and sank last month near the North Korean border.
The two men could face the death penalty if convicted of violating the National Security Law.