  Fluctuations of conserved quantities such as net-baryon, net-charge, and
net-strangeness numbers have generated considerable interest in the study of
the thermodynamic properties of the hot and dense QCD matter. Theoretical
calculations suggest that the off-diagonal cumulants of conserved charges along
with the diagonal cumulants can help better constrain the freeze-out parameters
and, therefore, help to map the QCD phase diagram. In this proceeding, we
briefly outline the recent STAR measurements on the second-order off-diagonal
cumulants of net-charge, net-proton, and net-kaon multiplicity distributions in
Au+Au collisions from the RHIC BES-I program in the energy range of
$\sqrt{s_{NN}}$ = 7.7-200 GeV. The measured cumulant ratios are compared to the
predictions from both thermal (HRG) and non-thermal (UrQMD) models.
