Choi Yun-jong, a suspect accused of sexually assaulting and killing a woman on a walking trail in Seoul's Gwanak District, has been referred to the prosecution.

The Seoul Gwanak Police Station on Friday transferred Choi on charges of rape and murder.

Asked why he committed the crimes as he was brought out of the police station, Choi denied he had planned the murder, saying it was accidental, while saying that he did not know when he began planning the crimes in response to a question on the timeline of his preparations.

Last Thursday, Choi allegedly attacked the victim, with whom he had no previous encounter, with brass knuckles before sexually assaulting and strangling her on a walking trail linked to a park in the district. The victim died two days later.

The police suspect that Choi had attacked her with the intent to kill based on preliminary forensic results that found the cause of the victim's death to be asphyxiation by strangling.

They also found that the suspect had searched "knuckles," "sexual assault" and "murder," on his smartphone and personal computer as well as news articles on a recent series of online threats to kill random people in public places.