Mossbauer and AC-susceptibility measurements have been carried out on the alloy series FeAl_1-xMn_x within the range 0.05<or=xhf) distributions at two iron sites. The charge density rises linearly with Mn concentration while B_hf increases nonlinearly with x indicating a polarized spin density of the itinerant electrons at the Fe nucleus due to the near neighbouring Fe and Mn magnetic moments. The onset of magnetism is explained by the formation of magnetic moment at the iron atom when Al atoms are removed and by the nearest neighbouring iron clustering. Magnetic measurements indicate the presence of mictomagnetic clusters and show a transition from paramagnetic state to magnetic glass state for all the alloys. No onset of ferromagnetism with increasing x was observed even at the concentration x=0.4, in contrast to that observed in FeAl_1-xCu_x at a lower concentration x=0.325. Comparison of the transition temperatures obtained from Mossbauer and AC susceptibility measurements indicate relaxations of the magnetic clusters.