After the detection of 60Fe from a nearby supernova in a terrestrial sample the search for SN produced radionuclides has been extended to the r-process radionuclide 244Pu. For this purpose an efficient chemical separation method has been developed to extract traces of plutonium from samples in the kilogram range. The accelerator mass spectrometry method for actinides was optimized for a nearly background free detection of plutonium isotopes with a high overall efficiency. Measurements of anthropogenic (i.e. a-bomb produced) plutonium isotopes in deep sea manganese encrustations have been carried out to examine the probability for plutonium to be incorporated in deep sea manganese encrustations and its mobility therein. In a first measurement of a pre-bomb layer of a ferromanganese crust a weak 244Pu signal has been detected, consistent with the SN signal suggested by the 60Fe data.