"The suspects encoded their communications and penetrated nearby secure Wifi networks, since two of the suspects did not even have an Internet connection at hom

"The suspects encoded their communications and penetrated nearby secure Wifi networks, since two of the suspects did not even have an Internet connection at home, the police said." Spain probably has a pretty rigorous internet/telephony monitoring aparatus as a result of it's internal terrorism problems, but I'm curious how they were tracked down after the wifi network was located. Did the police just search all nearby properties? Is there hardware that can locate the source of individual wifi broadcasts?