FRONTLINE, The Associated Press and SITU Research team up to present an exclusive visual investigation of the atrocities committed in the Ukrainian town of Bucha during Russia’s month-long occupation earlier this year.

Drawing on hundreds of hours of CCTV footage, intercepted phone calls and a 3D model of Bucha, the collaborative investigation maps the scope of the carnage — more than 450 deaths in all — and with forensic detail charts how Russian soldiers ran “cleansing” operations.

Also in this 2-part hour, the story of a family’s struggle to reunite after being separated at the U.S.-Mexico border.