A SOUTH Korean was jailed for life for the murder of his girlfriend, who police originally believed had accidentally choked to death while eating a live octopus.

A district court in Incheon, west of Seoul, convicted the defendant, identified only as Kim, and sentenced him to life imprisonment for what the judge described as a "heinous crime".

The case, with its accusations of police incompetence, has received enormous media and public attention in South Korea.

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

He later called reception to say his girlfriend, identified by her surname Yoon, had collapsed and stopped breathing after eating one of them. She was taken to hospital but died 16 days later due to brain damage.

Live octopus is a delicacy in South Korea but is a known choking hazard, since the still-moving suction cups can cause tentacle pieces to stick in a person's throat.

A baby octopus is often consumed whole, while larger varieties are cut up and the still-wriggling tentacles eaten with a splash of sesame oil.

A tentacle was found in Yoon's throat and both her family and police initially accepted Mr Kim's story that she accidentally choked to death. Her body was later cremated.

Police were forced to reopen the case after a TV program highlighted efforts by Yoon's father to have Mr Kim investigated, after discovering his daughter had taken out a life insurance policy just before she died.

Mr Kim was the sole policy beneficiary and collected 200 million won ($175,400).

Although Yoon's body had been cremated, the Incheon court found there was compelling "indirect evidence" to conclude that Mr Kim had killed Yoon for the insurance money.

"The most probable cause of death was suffocation by soft cloth, and there's no evidence to conclude choking to death by eating the octopus," a court spokesman said.

"The victim had always had difficulty chewing so it is unrealistic to believe she ate a huge octopus ... without even chopping it," the spokesman said.

It was not immediately clear if Mr Kim, who has continued to protest his innocence, would appeal the verdict.

