Distributed Fault Detection Using Relative Information in Linear Multi-Agent Networks★★The work from Daniel Silvestre was supported by the project FCT [UID/EEA/50009/2013] and with grant SFRH//BD/71206/2010, from Fundação para a Ciência e a Tecnologia. J. Hespanha was supported by the U.S. Army Research Laboratory and the U.S. Army Research Office under grants No. W911NF-09-1-0553 and W911NF-09-D-0001. C. Silvestre was supported by project MYRG117(Y1-L3)-FST12-MKM of the University of Macau.