I love reading crime fiction, but when I came to start writing it for children I discovered that the life of a schoolkid detective wasn't going to be easy to chronicle.
2) My hero would need to investigate interesting crimes. Which is obvious, really, but when you can't include murders, poisonings, stabbings etc etc, how do you get your hero involved in the world of crime in the first place? Clearly, having him investigate someone's stolen cellphone, or a missing sports shirt, might just possibly get a little dull for readers. He needed mysteries with a bit more meat to them. Just not dead meat, that's all. Which takes us to...
3) My hero would need complex, involving mysteries to tackle – cases which were significant, but not gruesome or out of his league. At this point, things became really interesting. I had a very specific set of perameters within which the stories had to function, and I had to find multiple plots which would present new and unusual scenarios to my readers.
So far, my schoolkid detective Saxby Smart has filled eight volumes of casefiles (twenty-four individual stories, since there are three stories in each book). I have to admit, each successive volume had been harder to write than the previous one (see 1, 2 and 3 above!), but he's still there, in his garden shed, with his battered old Thinking Chair and his files of notes.
Check out Simon Cheshire's Saxby Smart books here