Jeffrey Lewis, a satellite imagery expert who has seen the Maxar images, described the process of deducing what the images meant as "very straightforward."
"You see pictures on the ground that show bodies relative to cars and buildings, and in satellite images, you can see the lumps on the ground in the same position next to the same cars and buildings.
"What the satellite images show is that the bodies were present while the Russians controlled the area," said Lewis, who is director of the East Asia Nonproliferation Program at the Middlebury Institute of International Studies.
The Pentagon said on Monday it could not independently confirm the accounts of atrocities but had no reason to dispute them.
A Reuters reporter saw several dead civilians in the town, including one with his hands bound behind him. Local residents said hundreds of civilians had been killed.
Bucha's deputy mayor, Taras Shapravskyi, said 50 of the dead residents, found after Russian forces withdrew from the city late last week, were the victims of extra-judicial killings carried out by Russian troops. Ukrainian officials, including President Volodymyr Zelenskiy, have accused Moscow of war crimes.
"These are war crimes and will be recognised by the world as genocide," Zelenskiy said, speaking on television from Bucha, wearing body armour and surrounded by military personnel.
The deaths in Bucha, outside Kyiv, drew pledges of further sanctions against Moscow from the West, possibly including some restrictions on the billions of dollars in energy that Europe still imports from Russia.
President Joe Biden has accused Russian President Vladimir Putin of war crimes and called for a war crimes trial.
