How to find someone in Madrid

I was wondering how I can go about looking for a person that lives or lived (not sure if still lives there)in Madrid. I have a first and last name, possibly last known address and phone number, and last known place of employment. If anyone knows please let me know.

Thanks!
mvella@solutiontechnology.com

if your Spanish is fairly decent, try the Spanish Yellow Pages . From there you will be able to link to the "white pages". Would be definitely helpful, if the person you are seeking is Spanish, to have both his/her last names.