AP Beirut reporters Bassem Mroue and Sarah El Deeb, and regional news director Zeina Karam set out to learn exactly what led to the devastating Aug. 4 explosion of nearly 3,000 tons of ammonium nitrate at the city’s port: how it could have happened; how the shipment arrived in Lebanon in the first place, who knew about the stockpile’s existence and why no one did anything about it for seven years,

Mroue meticulously dug up documents that began appearing online, searching them for clues and contacting security, judicial and political authorities whose names appeared. El Deeb chased a local journalist who had been investigating corruption at Beirut port for years.

For days Mroue, El Deeb and Karam spoke to scores of eyewitnesses and officials, and reviewed material from the scene of the blast and around Beirut. The result was the most detailed, comprehensive lead-up to the blast, including what is known so far of the cargo, paper trail and the circumstances and missteps that led to the catastrophic explosion.

The story was cited by local and regional media outlets as one of the most authoritative and detailed accounts of the explosion, and it appeared in major international news outlets.