Open-source investigators forensically analyse digital evidence - social media posts, eyewitness videos, satellite imagery - to find the truth behind news events. Their techniques are now increasingly used by investigative journalists to achieve big impact. An investigation by The New York Times into civilian deaths from air and drone strikes has resulted in a policy change by the US military. Also in the programme - in the west it's headlined as "the Ukraine crisis", but how is the situation being reported in Russian and Ukrainian media?

Guests: Alexa Koenig, Executive Director, Human Rights Center, Haley Willis, Visual Investigations Reporter, The New York Times, Benjamin Strick, Investigations Director, Centre for Information Resilience, Alison Killing, Winner of the 2021 Pulitzer Prize in International Reporting, and Francis Scarr, Senior Digital Journalist, BBC Monitoring in Moscow.

Presenter: Katie Razzall

Studio engineer: Tim Heffer

Assistant producer: Emily Finch

Editor: Richard Hooper