A search for a supersymmetric top decay assuming a 100% branching ratio of $^* \rightarrow \mu^+ \mu ^- b $ is presented using a minimally supersymmetric model at an integrated luminosity of 19.5 fb−1. The datasets were recorded with the CMS detector at the LHC. Using Baysian marginalization, an upper limit on the cross section of this process is computed and a cut off point is calculated below which the data does not support the presence of the target decay. This cut off point was calculated to be around 780 GeV.