It’s been six months since the Nord Stream gas pipelines were ruptured by a series of explosions, leaking tons of methane into the environment and igniting an international whodunit. Russia, the United States, the United Kingdom, and an unnamed pro-Ukrainian group have all been accused of planting explosives on the Baltic Sea pipelines in recent months. But half a year since the sabotage took place, the mystery remains unsolved.

Digital sleuths are stepping in to help provide clarity around bombshell claims about who was behind the attacks. Open source intelligence (OSINT) researchers are using public sources of data in their efforts to verify or debunk the snippets of information published about the Nord Stream explosions. They’re providing a glimpse of clarity to an incident that’s shrouded by secrecy and international politics.

Since early February, multiple media reports have claimed to provide new information about who could have attacked the Nord Stream 1 and 2 pipelines on September 26. However, the reports have largely been based on anonymous sources, including unnamed intelligence officials and leaks from government investigations into the attacks.

First, American investigative journalist Seymour Hersh published claims that the US was behind attacks in a post on Substack. This was followed by reports in The New York Times and German publication Die Zeit claiming a pro-Ukrainian group was responsible. (European leaders have previously speculated Russia could be behind the attacks, and Russia has blamed the United Kingdom.) No country has claimed responsibility for the blasts so far, and official investigations are ongoing.

Each of the recent reports has provided little hard evidence to show what may actually have happened, while helping to fuel speculation. Jacob Kaarsbo, a senior analyst at Think Tank Europa, who previously worked in Danish intelligence for 15 years, says the claims have been “remarkable” but also “speculative” in nature. “In my mind, they don’t really alter the picture,” Kaarsbo says, adding the attacks look highly complex and would likely be “very hard to pull off without it being a state actor or at least with state sponsorship.”

In the absence of official information, OSINT researchers have been trying to plug the gaps by examining the claims of the new reports with public data. OSINT analysis is a powerful way to determine how an event may have unfolded. For instance, flight- and ship-tracking data can reveal movements around the world, satellite images show Earth in near real-time, while small clues in the backgrounds of photos and videos can reveal where they were taken. The techniques have uncovered Russian assassins, spotted North Korea evading international trading sanctions, identified potential war criminals, and documented pollution.

For the Nord Stream blasts, there was little OSINT available. Researchers identified “dark ships” in the area. But underwater, there are obviously limited data sources that can be tapped into—cameras and sensors don’t monitor every inch of the pipelines. “OSINT probably won’t break this case open, but it can be used to verify or strengthen other hypotheses,” says Oliver Alexander, an analyst who focuses on OSINT and has been closely looking at the Nord Stream blasts. “I do think that it’s more of a verification tool.”