Curing the infinite ghost tower in 4d Siegel superparticle

On an explicit example of the Siegel superparticle we study an alternative to the harmonic superspace approach. The latter seems to be the only method for quantizing infinitely reducible first class constraints currently avai lable. In an appropriately extended phase space, the infinite ghost tower i s effectively canceled by that coming from the sector of auxiliary variable s. After a proper BRST treatment the theory proves to be of rank two which correlates well with the results obtained earlier within the framework of t he harmonic superspace approach. The advantage of the novel technique, howe ver, is the existence of an explicit lagrangian formulation and the standar d spin-statistics relations which hold for all the variables involved.