Running a solo adventure is all about not knowing what is really going on until the end when the truth is revealed.
The way we can do this is by setting up what I called the briefing, to give you a decent start to the adventure, and then testing your assertions by using the oracle. If you make a successful forensic test, and you want to know if you find prints, you decide how likely you think it will be to find fingerprints (very unlikely on something that has been in seawater for a month, possibly) to very likely on a beer glass (who drinks beer wearing gloves?), then roll the oracle. If you get a strong positive you could decide that it is a strong clear print. The mixed results may be a partial print or confusion of prints, a strong negative may mean a complete absence of prints.
When you have your answer you add it to the other facts you think you have and start to form a hypothesis and then go looking for the evidence to support your hypothesis. The better you think your idea is, the more likely you can make the oracle questions.
There is still the very real chance that the oracle will shoot your ideas down, in which case you need to think about what is wrong. Is the person you suspect being framed? Is that why the evidence points to them? Who could have done that?
In this way you can build up a complex mystery, entirely improvised, and you really will not know who is guilty or innocent until the very end.
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