Abstract. In this paper we show that the two-point function for the three-loop chiral superstring measure ansatz proposed by Cacciatori, Dalla Piazza, and van Geemen [2] vanishes. Our proof uses the reformulation of ansatz given in [8], theta functions, and specifically the theory of the Γ 00 linear system on Jacobians introduced by van Geemen and van der Geer [6]. At the two-loop level, where the amplitudes were computed by D'Hoker and Phong [11,12,13,14,17,18], we give a new proof of the vanishing of the two-point function (which was proven by them). We also discuss the possible approaches to proving the vanishing of the two-point function for the proposed ansatz in higher genera [8,24,3].