  The frequency dependence of the AC conductivity is studied in a holographic
model of a non-fermi liquid that is amenable to both analytical and numerical
computation. In the regime that dissipation dominates the DC conductivity, the
AC conductivity is described well in the IR by a Drude peak despite the absence
of quasiparticles. In the regime where pair-production-like processes dominate
the conductivity there is no Drude peak. A scaling tail is found for the AC
conductivity that is independent of the charge density and momentum
dissipation. Evidence is given that this scaling tail $\sigma_{AC}\sim
\omega^m$ appears generically in quantum critical holographic systems and the
associated scaling exponent $m$ is calculated in terms of the Lifshitz and
conduction critical exponents.
