The police said Sunday they were looking for proof that a man who raped and beat a woman to death on Thursday had intended to kill her.

The woman in her 30s was assaulted with brass knuckles in an alleged rape at a park in Seoul’s Sillim-dong on Friday. As she was pronounced dead on Saturday, the assailant’s alleged crimes were changed from rape and assault to rape and murder.

"Since the victim has passed away, we changed the suspect’s charges to rape and murder,” said a Seoul Gwanak Police Station official.

South Korean law stipulates a life sentence or the death penalty as punishment for rape and murder, though no executions have been carried out for over 25 years.

Police said they were also focusing on analyzing the suspect’s past actions after a crime scene reenactment to determine whether he had intended to kill the woman in addition to raping her.

The police believe that the crime was premeditated, as the suspect identified with his surname Choi left his residence in Doksan-dong, southwestern Seoul around two hours before the crime and searched for his target at the park entrance.

Choi purchased the brass knuckles four months in advance. The suspect and the victim are not thought to have known each other.

While Choi has admitted that he purchased the brass knuckles with the intent to commit rape, Choi said that he had no intention to kill and that his attempted rape had failed.

The police plan to conduct an autopsy on the woman’s body on Monday to determine the specific cause of death. The police review committee is also planning to determine whether to release Choi’s identity this week.