Think about the NYT example I gave above. How did someone discover that their list of COVID deaths had a murder victim in it? Easy: they read the list, noticed that the 6th person was in his twenties, remembered that COVID doesn't kill such people unless they're already dying of something else and stuck his name into Google. That surfaced another news report about the murder. This is basic fact checking but the NYT didn't do it. The data was too good to check, so they didn't.