Actually I disagree. It really depends how you write it. Why don't you try and see. And after all an event is far more interesting to start a book with than nothing. In A Series of Unortunate Events, Mr. Poe informs the Baudelaires that their parents died in a fire within the first few pages. I think you can start with murder, as long as you write it very carefully. Why don't you try it first, and then ask if it works in the SYW, as opposed to asking first? Though there are guidelines, there really aren't rules in writing. And even those guidelines can be broken.
Good luck!