Jerry Buting, one of Making a Murderer subject Steven Avery's original lawyers, recently told Rolling Stone that "internet sleuths" (obsessed fans) found evidence in a photo of victim Teresa Halbach that lawyers missed. Buting hopes new evidence like this could change the entire case, by opening the possibility of another trial.
This new key evidence is literally "key" evidence. The picture, shown frequently on the news and in the Netflix docu-series, apparently shows Halbach holding a key fob with several keys. This is in contradiction to the one lone key police allegedly found when searching Avery's bedroom on November 8, 2005 (three days after finding nothing on their initial search on November 5, interestingly).
In the interview, Buting says he understands why people online are fascinated with the case, and that the help is not unappreciated. "We were only two minds. What I'm discovering is that a million minds are better than two. Some of these people online have found things with a screen shot of a picture that we missed."
This evidence might have helped Avery's defense team prove their case that Halbach's key was planted in his bedroom by police. And if Avery does get a new trial, the new evidence could be quite useful. So it turns out that all the amateur detectives who found themselves obsessively poring the Internet for clues weren't wasting their time after all. And you should now feel free to use this incident to justify any other weird, obsessive rabbit-hole trips down the Internet you might want to take in the future.