There is a body in the basement of the abandoned yellow home at the end of the street near the railroad tracks. The man is young, pale, a dried trickle of blood by his mouth, shot to death and left in the dark, and no one knows why the Russians brought him there, to a home that wasn't his.

There is a pile of toys near the stairs to the basement. Plastic clothespins sway on an empty line under a cold, gray sky. They are all that's left of normal on this blackened end of the street in Bucha, where tank treads lay stripped from charred vehicles, civilian cars are crushed, and ammunition boxes are stacked beside empty Russian military rations and liquor bottles.

The man in the basement is almost an afterthought, one more body in a town where death is abundant, but satisfactory explanations for it are not.

A resident, Mykola Babak, points out the man after pondering the scene in a small courtyard nearby. Three men lay there. One is missing an eye. On an old carpet near one body, someone has placed a handful of yellow flowers.

A dog paces by a wheelbarrow around the corner, agitated. The wheelbarrow holds the body of another dog. It has been shot, too.

This story is part of an ongoing investigation from The Associated Press and Frontline that includes the War Crimes Watch Ukraine i nteractive experience and an upcoming documentary.

Babak stands, a cigarette in one hand, a plastic bag of cat food in the other.

"I'm very calm today," he says. "I shaved for the first time."

At the beginning of their monthlong occupation of Bucha, he said, the Russians kept pretty much to themselves, focused on forward progress. When that stalled they went house to house looking for young men, sometimes taking documents and phones. Ukrainian resistance seemed to be wearing on them. The Russians seemed angrier, more impulsive. Sometimes they seemed drunk.

The first time they visited Babak, they were polite. But when they returned on his birthday, March 28, they screamed at him and his brother-in-law. They put a grenade to the brother-in-law's armpit and threatened to pull the pin. They took an AK-47 and fired near Babak's feet. Let's kill him, one of them said, but another Russian told them to leave it and go.

Before they left, the Russians asked him an excellent question: "Why are you still here?"

Like many who stayed in Bucha, Babak is older -- 61. It was not as easy to leave. He thought he would be spared. And yet, in the end, the stressed-out Russians accused him of being a saboteur. He spent a month under occupation without connection with the world, without electricity, without running water, cooking over a fire. He was not prepared for this war.

Maybe the Russians weren't either.

Around 6 p.m. on March 31 - and Babak remembers this clearly - the Russians jumped into their vehicles and left, so quickly that they abandoned the bodies of their companions.

Now he watches police and other investigators arrive, look at the bodies in the courtyard, and leave. He wonders when the bodies will be taken away so families can mourn. Down the road is an empty playground, steps away from six charred bodies. People don't know who they are.

"On this street we were fine," Babak says, taking stock of the occupation. In Bucha, everything is relative. "They weren't shooting anyone who stepped out of their house. On the next street, they did."

Walking through Bucha, a reporter encountered two dozen witnesses of the Russian occupation. Almost everyone said they saw a body, sometimes several more. Civilians were killed, mostly men, sometimes picked off at random. Many, including the elderly, say they themselves were threatened.

The question that survivors, investigators and the world would like to answer is why. Ukraine has seen the horrors of Mariupol, Kharkiv, Chernihiv and nearby Irpin. But the images from this town an hour's drive from Kyiv -- of bodies burned, bodies with hands bound, bodies strewn near bicycles and flattened cars -- have seared themselves into global consciousness like no others.

"It certainly appears to be very, very deliberate. But it's difficult to know what more motivation was behind this," a senior U.S. defense official said this week, speaking on condition of anonymity to discuss the military assessment.

The residents of Bucha, as they venture out of cold homes and basements, offer theories. Some believe the Russians weren't ready for an extended fight or had especially undisciplined fighters among them. Some believe the house-to-house targeting of younger men was a hunt for those who had fought the Russians in recent years in separatist-held eastern Ukraine and had been given shelter in the town.

Sometimes, they say, the Russians themselves explained why they killed.

In one backyard in Bucha are three graves, dug by neighbors too scared to put them elsewhere. One of the dead was killed on March 4, struck in the head with the butt of a rifle.

On March 15, a friend of the dead man was approached by Russians demanding his documents. They're at home, he said. On the way there, they passed the grave. He pointed it out. The next moment, witness Iryna Kolysnik says, the soldiers shot him.

"He was talking too much," one said, adding an expletive.

By the end, any shred of discipline broke down. "They went from normal soldiers to much, much worse," says Roman Skytenko, 24, who saw four civilian bodies on the street near his house.

Grenades were tossed into basements, bodies thrown into wells. An elderly man at a nursing home was found dead in his bed, apparently of neglect, while a younger person, perhaps a caregiver, lay outside, shot to death. Women in their 70s were told not to stick their heads out of their houses or they'd be killed. "If you leave home, I'll obey the order, and you know what the order is. I'll burn your house," Tetyana Petrovskaya recalls one soldier telling her.

Now that the Russians have left, bodies are being collected by searchers wary of booby traps and mines. The body bags are placed in rows at a cemetery. Some bags aren't fully closed. A glimpse shows the bloodied face of a young person. Another shows a pair of white sneakers. Mayor Anatoliy Fedoruk said the count of dead civilians was 320 as of Wednesday. Most died from gunshots, and some corpses with their hands tied were "dumped like firewood" into mass graves.

Vladyslav Minchenko is an artist who helps to collect the bodies. During the occupation, he found another way to help -- spotting Russians through binoculars and telling the "appropriate people" where they were. Three weeks ago, he says, he was discovered.

The Russians came and stripped him and put him near the wall to be shot. But in that final moment, something changed. The Russians had a list of Ukrainian military personnel to look for, and it happened that Minchenko was staying with one.

"I was almost killed," he says, "but someone said, 'This is not the guy from the list.'"

He worries the Russians will be back, with more experienced fighters who might not hesitate to fire.

Many Bucha residents describe similar, frightening encounters. A building was used as a base by the Russians; residents were forced to stay in the garbage-strewn basement. It was cold and crowded, with about 100 people. They used buckets for toilets. There was not enough food. Babies cried.

On March 3 or 4, one resident on her way into the shelter was told to stand near the bodies of several men who had been killed, some with their hands bound.

"I thought they'd shoot us right there," she says, not giving her name. As she stood there, crying, a Russian soldier told her not to be afraid, they only wanted to speak with men. Three days later, she was released. It is not clear why.

A few homes away stands 80-year-old Galyna Cheredynachenko. She leans on two canes near the end of her sidewalk, a bright pink scarf around her head. When the Russians came to her door in the early days of the occupation, they parked their tank in her front yard, almost crushing her flower bulbs.

She refused to go to the shelter. The Russians moved in with her instead. They cooked in her courtyard, slept in her house, used her kettle for tea. She gave them her tomatoes and cucumbers. They told her not to leave her room. "They weren't bad, they just wouldn't let me out," she says.

She is only beginning to learn about the town's real toll -- about how at least four people in her area were killed, all civilians, and how the Russians told people to bury the dead in their courtyards.

"I was born in World War II," Cheredynachenko says. "If you tell me the Nazis did this, I'd understand. I don't understand how the Russians can do this."

They got hungry, says another survivor, 63-year-old Nataliya Aleksandrova. They got cold.

At first, she says, the Russians behaved: "They said they had come for three days." But the war went on, and they started to loot. Clothing, shoes, alcohol, gold, money. They shot TV screens for no reason.

They feared there were spies among the Ukrainians. Aleksandrova says her nephew was detained on March 7 after being spotted filming destroyed tanks with his phone. He was accused of being a Ukrainian nationalist. Four days later, he was found in a basement, shot in the ear.

Days later, thinking the Russians were gone, Aleksandrova and a neighbor slipped out to shutter nearby homes and protect them from looting. The Russians caught them and took them to a basement.

"They asked us, 'Which type of death do you prefer, slow or fast?'" Grenade or gun?

"I told them I didn't want to die," she says. They were given 30 seconds to decide.

Suddenly the soldiers were called away, leaving Aleksandrova and her neighbor shaken but alive.

"I'm not saying everyone was crazy, but some were very bad people," she says. "Soldiers should have some dignity. They were just a gang of thieves."

The Russians became desperate when it became clear they wouldn't be able to move on Kyiv, says Sergei Radetskiy, who noticed fewer organized troop movements in the occupation's final days. The soldiers were just thinking about how to loot and get out. They were more nervous and aggressive.

"They needed to kill someone," he says. "And killing civilians is very easy."

In a silent neighborhood, the gate of a home is open. An elderly woman in a fur coat lies in the front doorway, face down. A dog, one of many roaming the streets, stands beside her and yips. Inside, curled on the worn wooden floor under the kitchen table, is another elderly woman.

No one seems to know how they died. They have been lying there since March 5, says a neighbor, Sergiy. "Shock is not enough to describe it." He believes a Russian sniper shot them at a distance.

Around the corner, on an empty street, a woman in a knitted cap watches from her gate. At a muffled blast from distant de-mining operations, she ducks in terror, grabbing her head. Then she sighs.

Valentyna Nekrutenko is 63 and spent the occupation with her husband, who is so ill he can barely stand. He lies on a mattress on their living room floor under blankets. Nekrutenko believes the war has shaken his mind. The dim home around them is scattered, too, with a half-made meal of bread and beetroot neglected near the sink.

Nekrutenko says she watched the Russians break into the house across the street. A piece of a mortar shell pierced her roof. Limping, not so well herself, she never went far, only going out for water.

Cut off for so long, she doesn't know about the bodies of the elderly women a few houses away. She doesn't know why the horrified world has come to her town to document the dead.

"Why come here?" Nekrutenko asks, honestly puzzled. "There's nothing important about Bucha."

From The Associated Press