  We demonstrate the control of electron-electron correlation in frustrated
double ionization (FDI) of the two-electron triatomic molecule D$_{3}^{+}$ when
driven by two orthogonally polarized two-color laser fields. We employ a
three-dimensional semi-classical model that fully accounts for the electron and
nuclear motion in strong fields. We analyze the FDI probability and the
distribution of the momentum of the escaping electron along the polarization
direction of the longer wavelength and more intense laser field. These
observables when considered in conjunction bear clear signatures of the
prevalence or absence of electron-electron correlation in FDI, depending on the
time-delay between the two laser pulses. We find that D$_{3}^{+}$ is a better
candidate compared to H$_{2}$ for demonstrating also experimentally that
electron-electron correlation indeed underlies FDI.
