  The $\omega$-, $\rho$- and $\phi$-resonance production and their dileptonic
decay in $\pi^- A$ reactions at 1.1 - 1.7 GeV/c are calculated within the
intranuclear cascade (INC) approach. The invariant mass distribution of the
dilepton pair for each resonance can be decomposed in two components which
correspond to their decay 'inside' the target nucleus and in the vacuum,
respectively. The first components are strongly distorted by the nuclear medium
due to resonance-nucleon scattering and a possible mass shift at finite baryon
density. These medium modifications are compared to background sources in the
dilepton spectrum from $\pi N$ bremsstrahlung as well as the Dalitz decays of
$\omega$ and $\eta$ mesons produced in the reaction. Detailed predictions for
$\pi^- Pb$ reactions at 1.3 and 1.7 GeV/c are made within several momentum bins
for the lepton pair.
