By Richard Allen Greene and Judy Kwon, CNN

(CNN) - A South Korean man was found crucified, local police told CNN on Thursday.

Police in Munkyuong said they were overwhelmed with the investigation and declined to provide further details.

But local media depicted an elaborate reconstruction of the crucifixion of Jesus, with the victim wearing a crown of thorns and dressed only in his underwear. He put nails into the cross first, then drilled holes in his hands and hung himself on the cross, reports said.

There was a wound in his side, reports said.

Police found nails, a hammer, an electric drill and pieces of wood near the body, as well as instructions on how to build a cross, and a note from the victim, reports said. The victim's family confirmed the handwriting was his, according to local media, which did not name the victim or say what was written in the note.

The body was found about 10 days after Good Friday, the day Christians believe Jesus was crucified.

South Korean reports said two smaller crosses were erected near the victim's. Biblical accounts say two thieves were crucified alongside Jesus on Golgotha.

South Korea is about 30% Christian, according to the U.S. State Department, which says Christianity is the largest single religious group in the country.

South Korean national police did not know whether there had ever been another case of crucifixion in the country.

Catholic commentator and author Lavinia Byrne, a former nun, pointed out that Christians' "voluntary embrace of suffering" was as old as the religion itself.

"You had a strand in the tradition which is known as 'red martyrdom,' literally the shedding of blood, literally following Jesus in his suffering," she said.

That ancient tradition faded when Roman persecution of the Christian church ended 1,600 years ago, but was succeeded by "what was called 'white martyrdom,'" when some Christians "voluntarily practiced extreme forms of celibacy and physical punishment following Jesus" for several hundred more years.

"The practice has always been there" in Christianity, she said.

Shiite Muslims also self-flagellate to commemorate what they see as the martyrdom of Ali, a nephew of Mohammed.

"It's entering into the suffering of Ali," she said.

Another expert on religion and mental health said he had never heard of a person re-enacting the crucifixion of Jesus to the point of death before, but that the South Korean victim was not necessarily insane.

"It's possible that this man suffered from mental illness, but without knowing the context you struggle to know more," said Simon Dein, an editor of the journal "Mental Health, Religion & Culture."

"It's not unknown for Christians and Shia Muslims to inflict extreme pain for atonement," he said. "It is thought that pain is spiritually purifying."

"Within Christianity now, there is a very small surviving element of asceticism," he said, citing examples of self-flagellation in Calabria, Italy, at Easter.

"In the Philippines, there is still crucifixion," he added. "Someone volunteers to be nailed to a cross," but is then taken down and given medical treatment.

The South Korean incident is "the the extreme end of it," he said.

The victim certainly could have been insane, said Dein, of University College London medical school.

"Within the context of religious delusions, people do do extreme acts of physical violence to themselves and others," he said. "Either he was so devout that he did this or he was mentally ill."