You hear a murder scene before you see it: The desperate cries of a new widow. The piercing sirens of approaching police cars. The thud, thud, thud of the rain drumming on the pavement of a Manila alleyway — and on the back of Romeo Torres Fontanilla.

Tigas, as Mr. Fontanilla was known, was lying facedown in the street when I pulled up after 1 a.m. He was 37. Gunned down, witnesses said, by two unknown men on a motorbike. The downpour had washed his blood into the gutter.

The rain-soaked alley in the Pasay district of Manila was my 17th crime scene, on my 11th day in the Philippines capital. I had come to document the bloody and chaotic campaign against drugs that President Rodrigo Duterte began when he took office on June 30: since then, about 2,000 people had been slain at the hands of the police alone.

I witnessed bloody scenes just about everywhere imaginable — on the sidewalk, on train tracks, in front of a girls’ school, outside 7-Eleven stores and a McDonald’s restaurant, across bedroom mattresses and living-room sofas. I watched as a woman in red peeked at one of those grisly sites through fingers held over her eyes, at once trying to protect herself and permit herself one last glance at a man killed in the middle of a busy road.

Not far from where Tigas was killed, I found Michael Araja, shown in the first photo below, dead in front of a “sari sari,” what locals call the kiosks that sell basics in the slums. Neighbors told me that Mr. Araja, 29, had gone out to buy cigarettes and a drink for his wife, only to be shot dead by two men on a motorcycle, a tactic common enough to have earned its own nickname: riding in tandem.

In another neighborhood, Riverside, a bloodied Barbie doll lay next to the body of a 17-year-old girl who had been killed alongside her 21-year-old boyfriend.

“They are slaughtering us like animals,” said a bystander who was afraid to give his name.

Many of the following images depict graphic violence.

I have worked in 60 countries, covered wars in Iraq and Afghanistan, and spent much of 2014 living inside West Africa’s Ebola zone, a place gripped by fear and death. What I experienced in the Philippines felt like a new level of ruthlessness: police officers’ summarily shooting anyone suspected of dealing or even using drugs, vigilantes’ taking seriously Mr. Duterte’s call to “slaughter them all.”

He said in October, “You can expect 20,000 or 30,000 more.”

On Saturday, Mr. Duterte said that, in a telephone call the day before, President-elect Donald J. Trump had endorsed the brutal antidrug campaign and invited him to visit New York and Washington. “He said that, well, we are doing it as a sovereign nation, the right way,” Mr. Duterte said in a summary of the call released by his office.

Beyond those killed in official drug operations, the Philippine National Police have counted more than 3,500 unsolved homicides since July 1, turning much of the country into a macabre house of mourning.

Some bodies were found on the streets with their heads wrapped in packing tape. Others were left with crude cardboard signs labeling victims as dealers or addicts. That is what happened with the two men in the video below, which was captured by a security camera outside Santa Catalina College, a private religious school for girls.

More than 35,600 people have been arrested in antidrug operations the government calls Project Tokhang. The name is derived from a phrase meaning “knock and plead” in Cebuano, Mr. Duterte’s first language.

In affluent neighborhoods of gated communities and estates, there is, indeed, sometimes a polite knock on the door, an officer handing a pamphlet detailing the repercussions of drug use to the housekeeper who answers. In poorer districts, the police grab teenage boys and men off the street, run background checks, make arrests and sometimes shoot to kill.

Government forces have gone door to door to more than 3.57 million residences, according to the police. More than 727,600 drug users and 56,500 pushers have surrendered so far, the police say, overcrowding prisons. At the Quezon City Jail, shown in the middle photo below, inmates take turns sleeping in any available space, including a basketball court.

My nights in Manila would begin at 9 p.m. at the police district press office, where I joined a group of local reporters waiting for word of the latest killings. We would set off in convoys, like a train on rails, hazard lights flashing as we sped through red traffic lights.

I kept daily diaries and audio recordings of these overnight operations, working with Rica Concepcion, a Filipino reporter with 30 years of experience.

We joined the police on numerous stings. We also went on our own to the places where people were killed or bodies were found. The relatives and neighbors we met in those places often told a very different story from what was recorded in official police accounts.

“Nanlaban” is what the police call a case when a suspect resists arrest and ends up dead. It means “he fought it out.” That is what they said about Florjohn Cruz, 34, whose body was being carted away by a funeral home when I arrived at his home in the poor Caloocan neighborhood just before 11 p.m. one night.

His niece said they found a cardboard sign saying “Pusher at Adik Wag Tularan” — “Don’t be a pusher and an addict like him” — as they were cleaning Mr. Cruz’s blood from the floor near the family’s altar, shown in the middle photo below.

The police report said, “Suspect Cruz ran inside the house then pulled a firearm and successively shot the lawmen, prompting the same to return fire in order to prevent and repel Cruz’s unlawful aggression.”

His wife, Rita, told me, between pained cries, that Mr. Cruz had been fixing a transistor radio for his 71-year-old mother in the living room when armed men barged in and shot him dead.

The family said Mr. Cruz was not a drug dealer, only a user of shabu, as Filipinos call methamphetamine. He had surrendered months earlier, responding to Mr. Duterte’s call, for what was supposed to be a drug-treatment program. The police came for him anyway.

As my time in the Philippines wore on, the killings seemed to become more brazen. Police officers appeared to do little to hide their involvement in what were essentially extrajudicial executions. Nanlaban had become a dark joke.

“There is a new way of dying in the Philippines,” said Redentor C. Ulsano, the police superintendent in the Tondo district. He smiled and held his wrists together in front of him, pretending to be handcuffed.

Mr. Cruz’s 16-year-old nephew, Eliam, and 18-year-old niece, Princess, said they had watched from a second-story porch as the plainclothes officers who had killed their uncle emerged from the house. Eliam and Princess said they heard the beep of a text message and watched as one of the men read it from his phone.

“Ginebra’s won,” he announced to the others, referring to Barangay Ginebra San Miguel, the nation’s most popular basketball team, which had been battling for the championship across town. The teenagers said the men celebrated the team’s victory as their uncle was carried out in a body bag.

Roel Scott, 13, is one of the boys in the photo above, at the spot where his uncle, Joselito Jumaquio, was slain by a mob of masked men. Mourners often place candles in the blood of the victim to honor them.

Roel said he was playing video games with Mr. Jumaquio, a pedicab driver who had also surrendered himself to the authorities, when 15 of the masked men descended quickly and silently over the shantytown called Pandacan.

Witnesses told us the men dragged Mr. Jumaquio down an alley and shouted at gathering neighbors to go back into their homes and turn the lights off. They heard a woman shout, “Nanlaban!” He’s fighting it out.

Two shots rang out. Then four more.

When it was quiet, the neighbors found the pedicab driver’s bloodied body — a gun and a plastic bag of shabu next to his handcuffed hands. The police report called it a “buy-bust operation.”

I also photographed wakes and funerals, a growing part of daily life under Mr. Duterte. Relatives and priests rarely mentioned the brutal causes of death.

Maria Mesa Deparine lost two sons in a single week in September. Both had turned themselves in to the police. Both were found dead under bridges.

Ms. Deparine said it took her three weeks to collect loans and donations totaling 50,000 pesos, about $1,030, to pay for the burial of her baby, Aljon, who was 23. We went with her to the funeral home where she pleaded with the owners to reduce the fees for his brother, Danilo, 36.

Danilo’s body, on the floor in the middle photo above, had already spent two weeks in the morgue, where the dead are stacked like firewood, with nothing separating them. The funeral directors agreed to a cut rate of 12,000 pesos, about $240, for a one-day wake instead of the usual week.

Ms. Deparine left, unsure whether she could come up with the sum, or whether Danilo would end up in a mass grave with other victims of the president’s drug war.

The killing disrupts every aspect of life. Family members told me that Benjamin Visda, in the coffin in the above photo, had stepped out of a family birthday party to grab something at a sari sari and was eating cake when eight men grabbed him. Within 20 minutes, his body had been dumped outside a police station.

The police called this, too, a buy-bust operation, and said that Mr. Visda, while handcuffed, tried to grab an officer’s gun — Nanlaban — so they shot him. The video below, also taken from a security camera, shows him being loaded alive onto a motorcycle, sandwiched between two masked men.

The same night Florjohn Cruz was killed, we found ourselves a few streets away an hour and a half later, at another home where a man had been murdered. It was raining that night, too.

We heard the wrenching screams of Nellie Diaz, the new widow, before we saw her — shown in the middle photo below — crumpled over the body of her husband, Crisostomo, who was 51.

Mr. Diaz grew up in the neighborhood, and worked intermittently, doing odd jobs. His wife said he was a user, not a dealer, and had turned himself in soon after Mr. Duterte’s election. She still thought it unsafe for him to sleep at home, and told him to stay with relatives. But he missed his nine children, and had returned days before.

Mr. Diaz’s eldest son, J.R., 19, said a man in a motorcycle helmet kicked in the front door, followed by two others. The man in the helmet pointed a gun at Mr. Diaz, J.R. said; the second man pointed a gun at his 15-year-old brother, Jhon Rex. The third man held a piece of paper.

J.R. said the man in the helmet said, “Goodbye, my friend,” before shooting his father in the chest. His body sank, but the man shot him twice more, in the head and cheeks. The children said the three men were laughing as they left.