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The decay ${D}^{+}\ensuremath{\rightarrow}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}{e}^{+}{\ensuremath{\nu}}_{e}$ has been studied in the Fermilab photoproduction experiment E691. The ratio of branching ratios, $\frac{B({D}^{+}\ensuremath{\rightarrow}{\overline{K}}^{*0}{e}^{+}{\ensuremath{\nu}}_{e})}{B({D}^{+}\ensuremath{\rightarrow}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{+})}$, is found to be 0.49\ifmmode\pm\else\textpm\fi{}0.04 \ifmmode\pm\else\textpm\fi{}0.05, corresponding to a ${D}^{+}\ensuremath{\rightarrow}{\overline{K}}^{*0}{e}^{+}{\ensuremath{\nu}}_{e}$ branching ratio of (4.5\ifmmode\pm\else\textpm\fi{}0.7\ifmmode\pm\else\textpm\fi{}0.5)%. The branching ratio to the nonresonant ${({K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+})}_{\mathrm{NR}}e{\ensuremath{\nu}}_{e}$ final state is found to be less than 0.7% at the 90% confidence level. The ${\overline{K}}^{*0}$ mesons have a ratio of longitudinal to transverse polarization of 2.4${\ifmmode\pm\else\textpm\fi{}}_{0.9}^{1.7}$\ifmmode\pm\else\textpm\fi{}0.2.