[en] Charm production in deep inelastic ep scattering was measured with the ZEUS detector using an integrated luminosity of 354 pb^-1. Charm quarks were identified by reconstructing D^± mesons in the D^±→K^-+π^±π^± decay channel. Lifetime information was used to reduce combinatorial background substantially. Differential cross sections were measured in the kinematic region 5< Q²<1000 GeV², 0.02< y<0.7, 1.5< p_T(D^±)<15 GeV and vertical stroke η(D^±) vertical stroke <1.6, where Q² is the photon virtuality, y is the inelasticity, and p_T(D^±) and η(D^±) are the transverse momentum and the pseudorapidity of the D^± meson, respectively. Next-to-leading-order QCD predictions are compared to the data. The charm contribution, F^cantic₂, to the proton structure-function F₂ was extracted.