We have used neutron-scattering and muon spin relaxation (μSR) to investigate the structural and magnetic properties of the β phase of elemental manganese doped with dilute amounts of indium. β-Mn is an example of a topologically frustrated antiferromagnetically correlated metal-but which remains paramagnetic at all temperatures. The addition of In to β-Mn results in a vast volume expansion of the lattice and would therefore be expected to have a major effect on the stability and localization of the Mn moment as observed in, for example, Ru- and Al-doped β-Mn alloys. We find that In doping in β-Mn results in a short-range ordered spin-glasslike ground state, similar to that of Al-doped β-Mn but with residual low-frequency spin fluctuations. This is in contrast to Ru doping which results in the stabilization of a long-range-ordered Mn moment © 2010 The American Physical Society.