Previously, the well-known Optimum Gaussian Detector (OGD) has been extended to the Multiple-Input Multiple-Output (MIMO) case where all transmit-receive subarrays are considered jointly as a system such that only one detection threshold is used [1, 2]. In this extension, all subarrays have been assumed to be widely separated and the transmitted waveforms are assumed to be orthogonal. However, the necessary separation needed for each subarray to be uncorrelated depends on several factors and it might not be possible to ensure that this condition is always respected, especially in the case of moving platforms. Moreover, perfectly orthogonal waveforms do not exist. Hence, we consider in this paper, a new robust MIMO detector that is able to maintain the same Probability of False Alarm (Pfa) irregardless of the correlation between the subarrays.