The Seoul court issued an arrest warrant for a 56-year-old sex offender surnamed Kang, who is suspected of murdering two women, saying he could flee.

Kang with 14 prior criminal convictions, including sex crimes, is accused of murdering women in their 40s and 50s before and after damaging his electronic anklet on Friday.

On Monday, police applied for an arrest warrant and the prosecution immediately filed it with the court.

Kang attended the court for the arrest warrant hearing Tuesday morning, which ended after about an hour. When reporters asked him about the motive for the crime afterward, he replied, “It is regrettable that I failed to kill more.”

Kang’s actions have fanned concerns over the efficacy of devices used to track convicted sex criminals. The electronic ankle device was introduced in 2008 to identify the location of ex-convicts through information delivered by base stations. The device helps track the location of a wearer, but doubts still remain as to whether it effectively prevents repeat offenses.

The Ministry of Justice’s budget for electronic anklets has continued to rise each year to reach 22.2 billion won ($19 million) this year, up 3.5 billion won from last year. Despite that, about 300 repeat crimes from ex-convicts wearing electronic anklets have been reported over the last five years. More than 80 cases of attempts to damage electronic anklets were reported.

When a wearer damages the device, they are subject to up to seven years in prison or a fine of 20 million won. But such strong punishments have not actually taken place. The average sentence so far is nine months in prison and 4.5 million won in fines.

Kwak Dae-kyung, a professor of police administration at Dongguk University, said, “Electronic anklets are a way to expect potential criminals to give up their crimes psychologically, but they cannot stop people who are willing to commit crimes.”

More authority and manpower should be given to police to prevent sex offenders from committing crimes again, he said.

After Kang damaged his electronic anklet, police visited his house five times. But they could not enter the house without a warrant.

The dispatched police also did not know Kang was a felon. Only senior police officials can look into criminal records of ex-convicts, to protect the human rights of the criminals. If police knew that Kang was a felon with 14 criminal convictions, they may have taken more aggressive actions and found the first dead body in his house. This could have prevented the second crime, experts say.

Lee Soo-jung, a professor of criminal psychology at Kyonggi University, said even low-ranking police officers need to be able to access the criminal records to find out who the target is.

Lee Woong-hyuk, a professor at Konkuk University’s policing department, said a fundamental problem is the society where public power cannot confidently be exercised. “This incident took place as a legal administration is passive and the responsibility of exercising public authority is only placed in hands-on police.”