  We apply data taken at the $e^+e^-$ collider LEP in the 1990's at
center-of-mass energy up to 209 GeV to constrain Dark Matter models with a
light leptophobic spin-1 mediator $R$. We assume that the dark sector particle
(DSP) is a spin-1/2 fermion $\chi$. This scenario is well studied in the
context of LHC searches for mediator mass from 100 GeV to several TeV. Emission
of the mediator off a quark or antiquark at LEP gives rise to di-jet plus
missing energy and 4-jet signatures, which we use to limit the relevant
couplings. We focus on scenarios with $2 m_\chi > m_R$, which are poorly
constrained by LHC data. We recast published searches by the ALEPH
collaboration. For $m_\chi < 20$ GeV the best bounds result from an analysis at
$\sqrt{s} \simeq M_Z$ of di-jet plus missing energy events. For heavier DSP but
$m_R < 70$ GeV meaningful bounds can be derived from a four jet analysis at
$\sqrt{s} = 183$ GeV. Unfortunately published searches using four jet final
states at $\sqrt{s} \simeq M_Z$ use only a small fraction of the total data
sample. Moreover, all published searches for di-jet plus missing energy final
states at $\sqrt{s} \geq 130$ GeV have poor efficiency for our model; we
therefore design new cuts that combine good background rejection with higher
efficiency. Re-analyzing the higher energy data using our new cuts, and an
analysis of the complete four jet data sample taken at $\sqrt{s}\simeq M_Z$,
can explore new regions of parameter space.
