I don't understand how Europol & Interpol both operate in the same arena?

Question

How can their investigations not overlap, when EU countries are involved? Isn't it unnecessary duplication, like having two CIAs? I read the website FAQ & they say they co-operate, and have different structures, but I don't see why European members need to use both intelligence agencies for the same areas?

http://www.europol.europa.eu/index.asp?page=faq
http://www.interpol.int/public/icpo/default.asp

Answer 1

No, I'll give you an example. A non-EU person (let's say hypothetically an American), commits a crime in the EU then flees to the U.S. Europol investigates the crime in conjunction with local police authorities, then involves Interpol to find the criminal outside of Europol's jurisdiction, and (depending on treaties between countries), arranges for the criminal to be turned over to Europol so he can be prosecuted for the crime in the country where it was committed.