The detection problem with multistatic radar systems is considered, resorting to the theory of detection of coherent target signals having a Gaussian probability density embedded in coherent Gaussian-distributed disturbances (i.e. clutter and/or directional jamming). A novelty of the paper is related to the capability of dealing with any type of time autocorrelation function of both target and disturbance. The spatial correlation among the signals scattered towards the receivers can also be taken into account. The latter topic is relevant when the receivers are deployed in a small area with respect to the spatial extension of the autocorrelation function of the scattered signals. Mathematical procedures have been conceived to derive the detection processors and for evaluating the corresponding performance, and have been applied to a number of original cases of interest. Finally, problems concerning the on-line implementation of the proposed processors family are discussed.