The Supreme Court Thursday upheld the acquittal of a former student who was imprisoned more than 20 years ago for aiding and abetting the suicide of a fellow activist and forging his will.

In 1991, Kang Ki-hoon was convicted of ghostwriting the will of Kim Ki-sul and persuading him to set himself on fire and jump to his death from a building at Seoul's Sogang University in protest against the then authoritarian government.

The highest court confirmed the not-guilty ruling Thursday, citing the lack of credibility of forensic evidence.

Often called the Korean version of France's "Dreyfus affair," the self-immolation by Kim in May 1991 came amid nationwide protests demanding the resignation of then President Roh Tae-woo.

The incident played a role in worsening public sentiments against student radicals.

After serving three years in prison, Kang sought a retrial.

The Truth and Reconciliation Commission, a special committee established in 2005 to reinvestigate past security-related cases, ruled in 2007 that the prosecutors pinned false charges against Kang. (Yonhap)