Lee Young-hak, the suspect in the death of his daughter's friend, picked the victim to satisfy his sexual desire, police said Friday.

Lee, 35, was arrested on Sunday for killing a 14-year-old girl from his daughter's school in his home in eastern Seoul and abandoning the body on a hill in the northeastern province of Gangwon earlier this month. His daughter is also in police custody for helping him dispose of the body.

The police have referred Lee's case to the prosecution, on charges of murder, sexual molestation, indecent act by force and body abandonment. They also sent the daughter to be charged for enticement and body disposal.

The investigation found that he told his daughter to invite the victim over as he needed someone to "play" his deceased wife, who committed suicide early last month, the Seoul Jungnang Police Station said at a press briefing.

When the victim passed out after sipping a drink his daughter gave to her that contained sleeping pills, Lee stripped her and carried out lewd acts on her body, the police said.

The autopsy of the victim has found no signs of sexual assault, which is consistent with the fact that Lee is sexually dysfunctional.

According to the police's profile on Lee, he is believed to have experienced bullying in his adolescence due to his jaw deformity caused by a rare genetic disease known as gigantiform cementoma.

Profilers also concluded Lee has a psychopathic tendency, possibly built over the years due to an unfortunate childhood. His daughter has mostly likely been in a master-servant relationship with the suspect in which she blindly followed his unreasonable orders and took part in the crime, the police said.

The murder, though, was not part of Lee's plan, the police said. He strangled her to death in a panic after she suddenly woke up and began to scream in fear as she found herself lying naked beside him.

"It is believed that he was afraid the victim might report to police," authorities said.

On Tuesday, he confessed to the murder. Up to that point, he had only admitted to dumping her body.

Lee's case has appalled the public, making headlines as he once appeared on a TV program a decade ago as a father devoted to curing his daughter's severe dental tumor she inherited from him. 

As he was transferred to a detention center, Lee offered an apology and said he is ready to pay the price.

"I am sorry," he told reporters. "Ever since my wife died, I've been high and not myself for a while... I do apologize... everything (that's happened) still feels like a dream." (Yonhap)