Why did you run?
What would be a good translation? Porque correo o porque corriste?
3 Answers
I would go with ¿Por qué corriste? if you address the person as tú. If you don't know the person, though, I would go with ¿Por qué corrió? (the usted form). Porque means 'because' rather than 'why'. As a general rule, if there are two words distinguished by an accent mark and one way it is a question word and the other way it is not, the question word has the accent mark.
Also, Late's suggestion has made me think that you may be dealing with someone who was running away, not just running, in which case it might be more appropriate to say ¿Por qué saliste corriendo? (tú) or ¿Por qué salió corriendo? (usted) or ¿Por qué te fuiste corriendo? (tú) or ¿Por qué se fue corriendo?
Julian has mentioned largarse. To use this, I would say, for Ud., ¿Por qué se largó? and for tú, ¿Por qué te largaste?
Please don't take this the wrong way, I mention this only to help. The polygraph question keep me intrigued for a while and I am guessing you want this for work.
Do you already have one (or more) of the Spanish for Law Enforcement books that are out there?

I'm not recommending any one in particular, I just know that I have seen some while looking through the Spanish Language section at my book store.
Book or no book, I don't blame you for "getting a second opinion" - but sometimes it is a little tough to access a computer and wait for someone that is familiar with your context and your field to come through.
Have you 'spoken' with Joe (this week he is disguised as Sherlock Holmes), he has a little (ahem) experience in law enforcement ... might be willing to share info. Try a PM.
¿por qué corriste?