We have investigated a previously unconsidered sidepath in muon cataly
zed fusion. We have found that high formation rates of metastable dt m
u molecules in t mu(2s)-D-2 collisions and their subsequent decay int
o t mu(1s) or d mu(1s) atoms open a return path for the muon from trit
ium to deuterium. This process can be considered as muon transfer from
t mu(2s) to d mu(1s) via three-body resonances of dt mu. This enlarg
es the d mu(1s) population and quenches the muon cycling rate, in agre
ement with experimental findings.