According to official statistics, the crime recorded in the past five years by persons aged 65 and over has increased by 45%. Serious crimes, including murder, arson, rape, and robbery, increased by 70% from around a thousand cases in 2013 to over 1800 in 2017.
In one case, in November, a man was arrested in the 1970s because he was a courier had attacked over a late package. When the police arrived, it turned out the man had forgotten that he had received the parcel two days earlier.
In August, another eighteen-year-old allegedly killed two officers and injured a neighbor in a water dispute. In April, a 69-year-old woman allegedly poured pesticides into a fish stew that was to be served at a village event.
But as they live longer, many can not support themselves financially as they grow older. About 60% of older Koreans are not entitled to the state pension, which was first introduced in 1988 or made mandatory until the late 1990s. In 2017, half lived in relative poverty.
"Since there is no job where older people can contribute to society, they feel disconnected and this can lead to hostility towards others, depression and antisocial behavior," said Cho Youn-oh, a professor and criminologist at Dongguk University in Seoul.
"Isolation and the feeling that nothing is lost could lead them to lose control and behave recklessly, and people who have more connections to society through family and work tend to have more self-control – that can stop them (committing crimes). "
] Older Prisoners
Even the country's prisons are struggling to cope with it. Older detainees can cause a wide range of health problems, including dementia, cancer and kidney problems – and often have to be separated from the rest of the population.
"Not only are they physically weaker than the younger ones, but if they are, younger people think that the chances of battling them are higher because of the generational gap and cultural differences," said Lee Yun-hwi, vice president Director of the Nambu Correctional Institute in Seoul.
CNN visited Nambu's Wing No. 2, where the elderly population of the prison lives – a wheelchair, a scale, and a device to measure blood pressure in the common area.
A typical Tuesday morning on the second wing begins at 9am with aggressively cheerful music being channeled through loudspeakers. About 30 elderly inmates in blue two-piece uniforms and white shoes are in the auditorium for an aerobics class.
While a song titled "What Wrong With My Age" is being played, the instructor urges them to make their protégés move back and forth, to bend and kick their legs. Their actions are slow – but for many inmates who spend most of their time in small cells, this is an important part of the day.
"It's good to prevent dementia, and I think it's emotionally healing," said Park, 71, whose full name and crime kept his identity hidden.
Park, which has been in Nambu for two years, believes that the rise in crime among older people is due to a lack of jobs and support for older people. "The crime rate increases when people have no money," he said.
Another inmate, 70-year-old Noh, wants South Korean society to take better care of the elderly.
Noh was born in the late 1940s in a huge chaos and instability in Korea when the peninsula was liberated from the Japanese occupation Before it plunged into civil war, millions of family members were separated and hundreds of thousands orphaned.
He said his generation had been through some of the hardest times in Korean history – yet without any savings or support from wider society.
Looking for a solution
The reintegration into society, of course, poses a significant problem for many inmates. About 30% of the older convicts commit crimes after their release – above the general recidivism rate of 20%.
Criminologist Cho said a social support network could make all the difference in preventing future violations. With South Korea already on track to join Japan as a "super-age society" in 2025, he said that the public needs to understand the difficult situation faced by many older citizens in order for broader support for such services and policies.
For today, one of the safest places for many elderly prisoners is the jail itself. When many inmates were released, Noh said, "They have no place to sleep or walk, no money to eat."
While he counted himself among the lucky ones, with a wife and children out there to support him, "prisoners who have spent 10 to 15 years in the house are afraid to be released because they can not go anywhere. "
Paula Hancocks and David Hawley of CNN contributed to their coverage.