The United Nations' high commissioner for human rights said Tuesday that Philippine President Rodrigo Duterte should be investigated for murder following comments he recently made about personally killing three suspected criminals, NBC News reports.

"The killings committed by Mr. Duterte, by his own admission ... clearly constitute murder," Zeid Ra'ad Al Hussein said in a statement. "It should be unthinkable for any functioning judicial system not to launch investigative and judicial proceedings when someone has openly admitted being a killer."

Duterte said earlier this month that as mayor of Davao he had patrolled the streets of the city looking for suspected criminals to kill.

"In Davao, I used to do it personally — just to show to the guys that if I can do it, why can't you?" Duterte explained to business leaders as to how he goaded police officers to gun down suspects.

"And I'd go around in Davao with a motorcycle, with a big bike around, and I would just patrol the streets, looking for trouble also," he said, according to The Manila Times. "I was really looking for a confrontation, so I could kill."

Duterte, who took office in late June, has taken a hard stance on the drug war. He campaigned on the promise that he would kill tens of thousands of criminals and wipe out the country's drug addicts.

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