The killing shocked the nation as Lee was publicly known after appearing on a TV show in the 2000s, which portrayed him as a poor man suffering from a rare dental disease while trying to eke out a living with a daughter who had the same incurable illness.

Lee earned the nickname of "molar father" after losing all but one molar while treating the disease.

"It is hard to imagine the pain that the victim would have gone through," the court said in its ruling. "The court therefore delivers the sentence to the defendant in the name of the rule of law and justice, having taken all situations into account."

The court berated Lee for not showing any regret or remorse, saying his demeanor shows he is unlikely to reform but will rather relapse into committing other similar -- or even worse -- crimes.

Lee was also indicted for working as his wife's pimp and forcing her to have sex with at least a dozen men. He also beat her and filmed her and the men on tapes. His wife took her own life in September.

The defendant faced fraud charges as well for raising 940 million won (US$873,000) through a fundraising campaign for his daughter's treatment and spending the money for himself.

It turned out that Lee had actually been living a luxurious life off government allowances and donations he received from those who took pity on him after seeing him on the TV show.

Legal experts noted that Lee's sentence can be considered heavy, as most recently-convicted murderers on death row were found guilty of multiple homicides.

However, it's unlikely that Lee will be executed. The law upholds the death penalty but South Korea has not carried it out since 1997, amid debates over its abolition.

If upheld by the top court, Lee will be the 62nd prisoner on death row by record, according to the Ministry of Justice. The latest death penalty was handed to a conscripted solider who killed five colleagues in a shooting spree at a military barrack in 2014. (Yonhap)