There are lots of ways to organize your material for a mystery roleplaying adventure.
Many GMs find a flowchart format useful. Turn left and follow the trail of clues that way, turn right and investigate another path.
But I confess, I am much more of a straight-line breadcrumbs sort of GM. Which means, I suppose, that I dole out the clues in succession, nearly all of them leading in the same direction.
There are still opportunities to go left or right. But it’s more of a Y branch that reconnects farther down the track, rather than an entirely new line of investigation. I’ve found that if either trail veers too far off, the PCs will either become hopelessly lost or lose interest.
That means for a linear investigation, you’ve got, at the most, one red herring to dangle in front of the players. One false lead maintains for the players the flavor of an investigation without derailing it. At worst, the PCs must backtrack to the point they followed the false clue.
Far better, in my experience, to return them to the main line as soon as possible. An investigative tree with too many – or too far-reaching branches – ultimately means there is an investigative track the PCs are missing. And if that’s the case, it essentially means the GM is designing two investigations. Regardless of how realistic separate wrongdoings might lead to the same perpetrator, for a game session requiring a few hours, it’s an inefficient use of everyone’s time.
That’s my case for making investigation scenarios linear. I’d love to hear about the approaches of other GMs. Share them in the comments section below.