A South Korean has been arrested for allegedly killing his girlfriend who was initially believed to have accidentally suffocated while eating a live octopus, a prosecutor said Tuesday.

After an investigation lasting many months the suspect identified only as Kim was formally arrested for murder last Friday, prosecutor Lee Geon-tae at Incheon city, west of Seoul, told AFP.

Kim would be charged within the next 10 days, he said.

“He’s still denying the charge... we believe enough evidence has been collected to charge him,” the prosecutor said without elaborating.

The suspect, now 31, checked into an Incheon motel with his girlfriend in April 2010 after buying two live octopuses from a local restaurant.

The man later called reception to say his girlfriend had collapsed and stopped breathing after eating one of them. She was taken to hospital but died 16 days later due to brain damage.

Her family initially believed the 24-year-old woman surnamed Yoon suffocated after a tentacle was found stuck in her throat. Her body was later cremated.

But Yoon‘s father later discovered the daughter had signed up for a life insurance policy a week before her death, with Kim as the beneficiary.

The story came to light after a TV station last year aired an interview with the father, who in September 2010 had asked prosecutors to investigate Kim.

Incheon police reopened the case and questioned Kim, who collected 200 million won ($189,400) in insurance money but denied any involvement in Yoon’s death.

Police said earlier they suspected Kim might have stuffed the octopus into Yoon’s throat or choked her with some other object such as a pillow.

Nakji, a small octopus native to Korean and Chinese waters, is a Korean delicacy with people swallowing still-wriggling portions. (AFP)