The microscopic magnetic local structure of layer-structured basic copper compounds Cu-2(OD)(3)CH3(CH2)(6)COO was determined by the solid-state high-resolution deuterium NMR above 190 K. The magnetic interaction in a copper layer was probed by the isotropic NMR shifts of OD- ions and could be approximated by a sum of 1D-Heisenberg chains in the high temperature region. Four copper chains with different exchange interactions J = -209, -201, -122, and -44 K were found from the temperature dependence of the four distinct deuterium NMR signals. The derived values of J almost reproduced the high temperature behavior of the magnetic susceptibility chi(A)T vs. T of this compound.