Police said Friday they were unable to tell whether Lee Ki-young, suspected of the murders of a taxi driver and an ex-girlfriend in Paju, Gyeonggi Province, is a psychopath or not.

"We've concluded that we are lacking materials with regards to some evaluation methods to assess (Lee's) psychopathy," said an official of Ilsan Dongbu Police Station.

According to police, they will not further conduct another psychopathy test, while prosecutors are likely to continue with such testing, as the case has been handed over.

In Korea, a Psychopathy Checklist-Revised test is used to measure psychopathy in a legal context, primarily to determine the criminal intent of the suspect.

The diagnosis, however, has little effect on the court decision over the gravity of the punishment.

Trial judges in Korea have the power to mitigate the punishment of a criminal in case he or she had an intellectual disability or was unable to remember committing the crime due to a mental disorder. But psychopathy, like other anti-social personality disorders, "is unlikely to have to do with memory loss or intellectual disability," a trial judge said.

Robbery and murder charges have been sought by police, which could be severely punished by at least life imprisonment.

Lee, 31, admitted to a car accident with a taxi driver while driving under the influence, tricking the 60-year-old into his house in Paju, beating him to death and stealing his credit card to buy luxury goods for personal purposes in December.

Police also revealed that Lee had confessed to killing his ex-girlfriend in Paju and discarding her body in August. The ex-girlfriend was found to be Lee's landlady. They had lived together for a few months before the murder.

Alongside the potential gravity of Lee's alleged crimes, footage revealed by media showed that Lee had bragged about his wealth -- which he had actually stolen from victims -- to strangers, and that Lee had forced a cat into water while smiling.