  Two searches for supersymmetric particles in final states containing a
same-flavour opposite-sign lepton pair, jets and large missing transverse
momentum are presented. The proton-proton collision data used in these searches
were collected at a centre-of-mass energy $\sqrt{s}=8$ TeV by the ATLAS
detector at the Large Hadron Collider and corresponds to an integrated
luminosity of 20.3 fb$^{-1}$. Two leptonic production mechanisms are
considered: decays of squarks and gluinos with $Z$ bosons in the final state,
resulting in a peak in the dilepton invariant mass distribution around the
$Z$-boson mass; and decays of neutralinos (e.g. $\tilde{\chi}^{0}_{2}
\rightarrow \ell^{+}\ell^{-}\tilde{\chi}^{0}_{1}$), resulting in a kinematic
endpoint in the dilepton invariant mass distribution. For the former, an excess
of events above the expected Standard Model background is observed, with a
significance of 3 standard deviations. In the latter case, the data are
well-described by the expected Standard Model background. The results from each
channel are interpreted in the context of several supersymmetric models
involving the production of squarks and gluinos.
