Detection protocols that involve several steps of measurement (“composite measurement protocols”) have been introduced by Aharonov, Albert and Vaidman [Y. Aharonov, D. Z. Albert, and L. Vaidman, Physical Review Letters 60, 1351 (1988).]. Their “Weak Value” protocol consisted of a weak measurement followed by a subsequent strong one, whose role is to post-select the former.  Here we extend this concept to a composite protocol, that consists of 3 measurement steps – weak , weak, and strong—which are non-local in space and in time. This protocol is applied to an electronic Mach-Zehnder interferometer, and is designed to manifest the non-local character of quantum mechanics on both the level of a single-particle and many-body phenomena. The weak-weak-strong sequence enables one to select non-causal Keldysh contributions to the current through the interferometer.  Selection of these Aharonov-Bohm flux sensitive contributions may greatly increase the measured visibility. We find conditions where, unlike common practice, many-body fluctuations do not suppress the visibility resulting from this protocol.