Study of the decays D→K3π

We report measurements of the decays D 0 →K #75 π + p + p #75 , D + →K 0 π + p + p #75 , D + →K #75 π + p + p 0 , and D 0 →K 0 π + p #75 p 0 from Fermilab photoproduction experiment E691. A complete resonant substructure analysis is used to determine the relative fractions and phases of amplitudes contributing to the decays D 0 →K #75 π + p + p #75 , D + →K 0 π + p + p #75 , and D + →K #75 π + p + p 0