With the material quality of undoped indium nitride significantly improved, attention has more recently turned towards achieving control of the electrical properties of this infrared bandgap semiconductor. Of the candidate acceptors, only Mg has been reported in detail, primarily as it is the acceptor of choice for GaN and GaInN. There are several other possibilities, however, which may be worth considering. In this paper, we describe the in situ doping of InN using Mn in a plasma-assisted molecular beam epitaxy process. Evidence of surfactant behaviour is observed in both in situ reflection high-enegy electron diffraction (RHEED) and ex situ scanning electron microscopy (SEM). Although electrical measurements are difficult to interpret due to the presence of an electron accumulation layer on the surface, photoluminescence (PL) measurements reveal a number of low-energy features previously unreported in this material, and may be correlated to Mn forming a deep acceptor.