When news first broke in early August about mysterious incidents involving U.S. diplomats in Cuba, the AP was all over the story, beating the competition to several key early details. These included talk among officials about a possible “sonic attack” and suspicions that ranged from Cuban culpability to possible intervention by an outside culprit like Russia.

But so many questions were left unanswered. And with the FBI deep into one of the most perplexing investigations in modern diplomatic history, U.S. officials in the State Department, White House and elsewhere were saying as little as possible about what they were learning.

That’s when the Washington bureau put together a multi-beat team of reporters to try to put the pieces together. Their comprehensive work wins Beat of the Week.

A source with direct knowledge of the attacks provided unreleased insights on the victims' reported symptoms and some of the places they were going for treatment.

Trying to shed light on what one former CIA official called “just mystery after mystery after mystery,” diplomatic reporters Josh Lederman and Matthew Lee tapped their best sources and scoured Washington for anyone who knew anything. Caribbean news director Michael Weissenstein plugged into his extensive network of U.S., Cuban and international officials in Havana. Medical writer Lauran Neergaard reached out to experts in the scientific community. And Rob Gillies in Toronto and Angela Charlton in Paris broke ground with their contacts.

Justice Department reporter Eric Tucker, national security editor Bradley Klapper and Latin American news manager Ben Fox also contributed reporting. Klapper and Washington-based international investigations editor Trish Wilson steered the effort.

The AP’s investigation gained speed when investigative reporter Jake Pearson in New York spoke to someone with direct knowledge of the attacks, providing unreleased insights on the types of symptoms that victims were reporting and some of the places they were going for treatment. It gave reporters a start on tying the symptoms to what might be causing them.

The reporters started getting more detail about the strange, narrowly focused intensity of the attacks. That’s when Lee got a fascinating presentation of how the incidents appeared to be happening. The source literally showed how you could be attacked in one place and, taking a couple of steps to the side, safe just a few feet away. Lederman confirmed the explanation with others familiar with the investigation.

Lederman got word of a hotel among the sites of attacks. In Havana, Weissenstein identified it as the Spanish-run Hotel Capri. Lederman and Lee quickly confirmed it.

When Lederman heard French diplomats might have been affected, Charlton got an initial wave off. But persistence paid off, as an official later explained to her how French embassy staffers were tested for signs of possible sonic attack. Those tests came back negative, but the episode showed the growing concerns. Gillies confirmed several Canadian households were hit and that Royal Canadian Mounted Police were investigating as well in the Cuban capital.

The team broke the fresh detail in the first story of a three-part series.

The AP team pieced together Castro’s unreported conversation with the top U.S. envoy in Havana.

Then came Raul Castro’s role. Weissenstein and Lee both heard how Castro’s personal denial and apparently genuine concern had surprised U.S. officials, who would have expected a lower-level response and possible indignation over the allegations. With Lederman, they pieced together Castro’s unreported conversation with top U.S. envoy Jeffrey DeLaurentis in Havana. The Castro story provided a fascinating behind-the-scenes look at the diplomacy between U.S. and Cuba amid the grave suspicions of a possible act of aggression.

Infographic

Sonic attacks identified as a potential cause of the ailments affecting U.S. diplomats in Cuba.

AP / KEVIN VINEYS

As the AP moved closer to publishing, the reporters went back to their sources. Now able to present the fruits of the investigation, they were able to glean new details about the working theories that the U.S. is pursuing as possible explanations for who was causing the incidents, with what instruments and why. It made for a fascinating finale to the series that put readers in the war room, as it were, of the investigators trying to solve the riddle. Each of the three stories in fact garnered extensive attention.

The reporting thrust the Cuba story into the center of America's foreign policy discussion once again. Probed about the new reporting on Sept. 17, Secretary of State Rex Tillerson suggested the U.S. could potentially close its Havana embassy. That came after several Republican senators piggybacked off the AP's reporting in urging Tillerson to kick out Cuba's diplomats in the U.S.

Lederman appeared on PBS' "NewsHour," Fox News, WCBS radio and MSNBC's "Rachel Maddow Show," in which the host repeatedly praised the AP's reporting, presented screen shots of the stories and read directly from the text. The various stories tallied more than 1,300 customer uses, with high engagement and social media metrics.

For painstaking work that shed light on a perplexing and disturbing mystery, Lederman, Lee, Weissenstein, Neergard and Gillies win the $500 prize.