Mr Biden said “this guy is brutal” and insisted more needs to be done.
He added: “You saw what happened in Bucha – he is a war criminal.
“But we have to gather all the detail so this can have a war crimes trial."
Mr Biden’s intervention follows the publication of satellite images by Maxar, the earth observation company.
U.S. President Joe Biden
LEAH MILLIS
Russian President Vladimir Putin
Reuters
The Kremlin insists the images have been staged by Ukraine, albeit had no evidence to back this up.
US officials say they are supporting a team of international prosecutors heading to Bucha to collect evidence.
The Ukrainian government said the bodies of 410 civilians had been found around Kyiv,starting a war crimes investigation.
Some were discovered in mass graves and others appeared to have their hands tied.
Moscow's ambassador to the UN said Russia would present "empirical evidence" to the UN Security Council in a bid to prove Western statements were lies.
At a press conference in New York, Vasily Nebenzya accused Ukraine and its "Western sponsors" of carrying out a false flag attack on its own people.
In Bucha, witnesses have described Russian soldiers firing on men fleeing after refusing to allow them to leave through humanitarian corridors.