High-resolution X-ray spectra were recorded by the High-Energy Electronic X-ray (HENEX) spectrometer from a variety of targets irradiated by the Omega laser at the Laboratory for Laser Energetics. The HENEX spectrometer utilizes four reflection crystals covering the 1-20 keV energy range and one quartz(1 0 Γ1 1) transmission crystal (LaueΒ΄geometry) covering the 11-40 keV range. The timeintegrated spectral images were recorded on five CMOS X-ray detectors. In the spectra recorded from krypton-filled gasbag and hohlraum targets, the helium-like K-shell transitions n ΒΌ 122, 1-3, and 1-4 appeared in the 13-17 keV energy range. A number of additional spectral features were observed at energies lower than the helium-like n ΒΌ 123 and n ΒΌ 124 transitions. Based on computational simulations of the spectra using the FLYCHK/FLYSPEC codes, which included opacity effects, these additional features are identified to be inner-shell transitions from the Li-like through N-like krypton charge states. The comparisons of the calculated and observed spectra indicate that these transitions are characteristic of the plasma conditions immediately after the laser pulse when the krypton density is 2 Γ 10 18 cm Γ3 and the electron temperature is in the range 2.8-3.2 keV. These spectral features represent a new diagnostic for the charge state distribution, the density and electron temperature, and the plasma opacity. Laboratory