This paper considers the problem of collaborative compressive detection under a physical layer secrecy constraint. More specifically, we consider the problem where the network operates in the presence of an eavesdropper who wants to discover the state of the nature being monitored by the system. We show that the security performance of the system can be improved by using cooperating trustworthy nodes that assist the Fusion Center (FC) by providing falsified data to the eavesdroppers. We also consider the problem of determining optimal system parameters which maximize the detection performance at the FC, while ensuring perfect secrecy at the eavesdropper.