We propose an investigation of the magnitude and fluctuations of internal magnetic fields in Mn-doped ZnGeP2. This chalcopyrite structured semiconductor has a ferromagnetic (FM) transition above 300K, thus is attractive for potential spin-based electronics applications. We will use the muon spin depolarization in magnetic fields applied parallel to the initial polarization to probe changes in the relaxation function associated with the onset of FM order near 312K and also near a transition to the AFM ground state present below 47K. Critical questions are to what extent the magnetism is transferred from Mn ions to the semiconducting charge carriers and whether the internal fields are uniform throughout the sample or whether FM order is confined to small regions suggesting that FM properties may be from a secondary MnP phase. This project is part of P.W. Mengyan's PhD research.