During their meeting, Gowan recorded his entire story before his death in 2018.
That conversation, along with classified documents made available to the BBC, led to the second season of the Buried podcast, called The Last Witness.
“In this series, we try to uncover the truth about what is beneath our feet, hear from the communities affected, and understand how something so insidious could stay buried for so long,” Sheen added.
“It’s about seeking answers, but also about responsibility – what we do now matters for the future of these communities.”
The two-episode series will meet with members of the affected communities, as well as forensic scientists and medical experts on his search for the truth.