MANILA >> Philippine senators opened an inquiry into the killings of more than 1,700 suspected drug dealers and users amid a crackdown spearheaded by President Rodrigo Duterte, with witnesses accusing some policemen of gunning down suspects or being involved in illegal drugs.

Sen. Leila de Lima, who heads the Senate justice committee leading the investigation, said that she was worried about the widespread killings, and that law enforcers and vigilantes may be using the crackdown “to commit murder with impunity.”

At least 1,779 drug suspects have been killed, including 712 who were gunned down in clashes with police, with the rest being slain in still-unclear circumstances, possibly by anti-crime vigilantes, national police chief Director-General Ronald dela Rosa told the senators Monday, adding that he did not condone extrajudicial killings.

The high number of deaths has alarmed human rights groups and leaders of the dominant Roman Catholic church, as well as the United States and U.N.-appointed human rights experts, who have warned the Philippine government and its officials that they could be held liable amid the widespread killings.

Another senator, Antonio Trillanes IV, asked dela Rosa why the police have failed to stop the killings by suspected anti-crime vigilantes, including motorcycle-riding gunmen.

“This is like anarchy,” Trillanes said. “It’s continuing under your watch.”

Trillanes warned policemen who might get involved in extrajudicial killings that they would be held criminally liable and convicted despite an assurance from Duterte that he would defend them if they face criminal and human rights charges while fighting crime.

“What I’m saying, general, is the world revolves,” Trillanes told dela Rosa and other police generals at the hearing, citing instances when military and police personnel were criminally charged for heeding unlawful orders.

“President Duterte is in position now, but what if his successor will prioritize human rights and conduct investigations?” he asked.

The brash Duterte, who built a name as a tough crime-busting mayor before rising to the presidency in June, has repeatedly threatened criminals, especially drug dealers, with death, which dela Rosa has emulated and even joked about. After facing criticism, both have clarified that policemen were under orders to shoot only if their lives are threatened.

Harra Besorio, one of a dozen witnesses scheduled to testify before the Senate committee, told the senators that policemen illegally arrested her boyfriend and his father, and beat them up in front of her. Neighbors then took them to a police anti-drugs station, where they were shot and killed last month, she said.

While searching her house without any warrant, one of the policemen forcibly removed the underwear of her 2-year-old daughter to check if the child was used to hide illegal drugs but found nothing, Besorio said in the nationally televised inquiry, acknowledging that her husband had peddled drugs to feed his family.

Two policemen accused of shooting Besorio’s boyfriend and his father argued that the suspects fought back and one tried to grab a police officer’s gun, but Commission on Human Rights official Gilbert Boiser said that was unlikely because an investigation showed the two suspects have been weakened by the beatings and were already in police custody in a station when they died, adding that each was shot three times.

“There were human rights violations,” Boiser said.

The two policemen accused in the killings of Besorio’s boyfriend and his father have been charged with murder, police said.

Another witness, Mary Rose Aquino, testified that her poor father, accompanied by her mother, had peddled drugs supplied by policemen and then remitted the money to them. In June, however, her parents were called by the policemen and the two were never seen alive again, she told the senators.

Duterte, a former state prosecutor, has been hypersensitive to criticism of his anti-drugs campaign and accused de Lima last week of having an affair with her driver, who allegedly collected protection money from detained drug lords when she was still the justice secretary. De Lima denied any wrongdoing and vowed to proceed with her Senate committee inquiry of the massive killings.

Over the weekend, Duterte threatened to withdraw the Philippines from the United Nations after two of its appointed human rights experts expressed concerns about the drug killings. However, Foreign Secretary Perfecto Yasay Jr. said Monday that the Philippines has no plans to break off from the U.N., adding that Duterte was expressing his disappointment over the experts’ criticisms and was hungry and tired when he uttered those remarks.