Turbine engine systems for interstage particle separation in multistage radial compressors are disclosed. The multistage radial compressor system includes an interstage region positioned between a first stage radial compressor and a second stage radial compressor. The interstage region includes a radially-outward oriented section, a longitudinally-oriented section, and a radially-inward oriented section. The radially-outward oriented section transitions to the longitudinally-oriented section at a first approximately 90-degree bend, and the longitudinally-oriented section transitions to the radially-inward oriented section at a second approximately 90-degree bend. The multistage radial compressor system further includes a particle separation system including an extraction slot and an aspiration slot located downstream from the extraction slot. The particle separation system is positioned along the interstage region outside of the air flow path. The extraction slot fluidly connects with a scavenge plenum, and the aspiration slot allows air from the scavenge plenum to recirculate back into the air flow path.