Observation of $ {\chi }_{cJ}\to 3{K}_{S}^{0}{K}^{\pm }{\pi }^{\mp }$

By analyzing $ (2712.4\pm 14.3)\times {10}^{6}\text{}\text{}\psi (3686)$ events collected with the BESIII detector operating at the BEPCII collider, the decays $ {\chi }_{c0,1,2}\to 3{K}_{S}^{0}{K}^{\pm }{\pi }^{\mp }$ are observed for the first time with statistical significances greater than $ 10\sigma $. The branching fractions of these decays are determined to be $ \mathcal{B}({\chi }_{c0}\to 3{K}_{S}^{0}{K}^{\pm }{\pi }^{\mp })=(7.95\pm 0.50\pm 0.65)\times {10}^{-5}$, $ \mathcal{B}({\chi }_{c1}\to 3{K}_{S}^{0}{K}^{\pm }{\pi }^{\mp })=(2.62\pm 0.08\pm 0.19)\times {10}^{-4}$, and $ \mathcal{B}({\chi }_{c2}\to 3{K}_{S}^{0}{K}^{\pm }{\pi }^{\mp })=(1.72\pm 0.07\pm 0.15)\times {10}^{-4}$, where the first uncertainties are statistical and the second systematic.