I just watched and finished the anime for the first time a week or so ago. I remember seeing arguments about this on CE years ago where some people said if it were real, most of CE would get caught. I didn't have any opinion since I hadn't seen the anime at the time.
Now that I've seen it, I feel like there is absolutely no way someone is going to get caught if a Death Note magically showed up in this world. For one, some super genius detective like L figuring it out is EXTREMELY unlikely. Two, most people aren't just going to sit around and watch the local news and then kill off criminals they see on TV anyway. Three, tons of people suspiciously die right now as is. No one (who's taken seriously at least) is suspecting a Death Note right now. Four, in the real world, no one is going to believe such a thing/power exists unless the owner was killing multiple people all at once in the most obvious way. And even then, it would probably take a while before they suspect some kind of magic. Like if a bunch of people died at an event on TV or something, people would suspect poisoning.
Twitch: https://www.twitch.tv/kid_prodigy23