  Using two novel methods, pair invariant mass ($m_{inv}$) and comparative
measurements with respect to reaction plane ($\Psi_{\rm RP}$) and participant
plane ($\Psi_{\rm PP}$), we isolate the possible chiral magnetic effect (CME)
from backgrounds in 200 GeV Au+Au collisions at STAR. The invariant mass method
identifies the resonance background contributions, coupled with the elliptic
flow ($v_{2}$), to the charge correlator CME observable ($\Delta\gamma$). At
high mass ($m_{inv}>1.5$ GeV/$c^{2}$) where resonance contribution is small, we
obtain the average $\Delta\gamma$ magnitude. In the low mass region
($m_{inv}<1.5$ GeV/$c^{2}$), resonance peaks are observed in
$\Delta\gamma$($m_{inv}$). An event shape engineering (ESE) method is used to
model the background shape in $m_{inv}$ to extract the potential CME signal at
low $m_{inv}$. In the comparative method, the $\Psi_{\rm RP}$ is assessed by
spectator neutrons measured by ZDC, and the $\Psi_{\rm PP}$ by the
2$^{nd}$-harmonic event plane measured by the TPC. The $v_{2}$ is stronger
along $\Psi_{\rm PP}$ and weaker along $\Psi_{\rm RP}$; in contrast, the
magnetic field, mainly from spectator protons, is weaker along $\Psi_{\rm PP}$
and stronger along $\Psi_{\rm RP}$. As a result, the $\Delta\gamma$ measured
with respect to $\Psi_{\rm RP}$ and $\Psi_{\rm PP}$ contain different amounts
of CME and background, and can thus determine these two contributions. It is
found that the possible CME signals with background isolation by these two
novel methods are small, on the order of a few percent of the inclusive
$\Delta\gamma$ measurements.
