/usr/include/relion-1.3/ is in librelion-dev-common 1.3+dfsg-2.
This file is owned by root:root, with mode 0o755.
..
/usr/include/relion-1.3/relion.h
/usr/include/relion-1.3/src/
/usr/include/relion-1.3/src/Healpix_2.15a/
/usr/include/relion-1.3/src/Healpix_2.15a/arr.h
/usr/include/relion-1.3/src/Healpix_2.15a/cxxutils.h
/usr/include/relion-1.3/src/Healpix_2.15a/datatypes.h
/usr/include/relion-1.3/src/Healpix_2.15a/geom_utils.h
/usr/include/relion-1.3/src/Healpix_2.15a/healpix_base.h
/usr/include/relion-1.3/src/Healpix_2.15a/lsconstants.h
/usr/include/relion-1.3/src/Healpix_2.15a/message_error.h
/usr/include/relion-1.3/src/Healpix_2.15a/openmp_support.h
/usr/include/relion-1.3/src/Healpix_2.15a/pointing.h
/usr/include/relion-1.3/src/Healpix_2.15a/vec3.h
/usr/include/relion-1.3/src/args.h
/usr/include/relion-1.3/src/assembly.h
/usr/include/relion-1.3/src/autopicker.h
/usr/include/relion-1.3/src/backprojector.h
/usr/include/relion-1.3/src/complex.h
/usr/include/relion-1.3/src/ctf.h
/usr/include/relion-1.3/src/ctffind_runner.h
/usr/include/relion-1.3/src/displayer.h
/usr/include/relion-1.3/src/error.h
/usr/include/relion-1.3/src/euler.h
/usr/include/relion-1.3/src/exp_model.h
/usr/include/relion-1.3/src/fftw.h
/usr/include/relion-1.3/src/filename.h
/usr/include/relion-1.3/src/funcs.h
/usr/include/relion-1.3/src/gcc_version.h
/usr/include/relion-1.3/src/gui_entries.h
/usr/include/relion-1.3/src/gui_jobwindow.h
/usr/include/relion-1.3/src/gui_mainwindow.h
/usr/include/relion-1.3/src/healpix_sampling.h
/usr/include/relion-1.3/src/image.h
/usr/include/relion-1.3/src/macros.h
/usr/include/relion-1.3/src/mask.h
/usr/include/relion-1.3/src/matrix1d.h
/usr/include/relion-1.3/src/matrix2d.h
/usr/include/relion-1.3/src/memory.h
/usr/include/relion-1.3/src/metadata_container.h
/usr/include/relion-1.3/src/metadata_label.h
/usr/include/relion-1.3/src/metadata_table.h
/usr/include/relion-1.3/src/ml_model.h
/usr/include/relion-1.3/src/ml_optimiser.h
/usr/include/relion-1.3/src/multidim_array.h
/usr/include/relion-1.3/src/numerical_recipes.h
/usr/include/relion-1.3/src/parallel.h
/usr/include/relion-1.3/src/particle_polisher.h
/usr/include/relion-1.3/src/particle_sorter.h
/usr/include/relion-1.3/src/postprocessing.h
/usr/include/relion-1.3/src/preprocessing.h
/usr/include/relion-1.3/src/projector.h
/usr/include/relion-1.3/src/rwIMAGIC.h
/usr/include/relion-1.3/src/rwMRC.h
/usr/include/relion-1.3/src/rwSPIDER.h
/usr/include/relion-1.3/src/strings.h
/usr/include/relion-1.3/src/symmetries.h
/usr/include/relion-1.3/src/tabfuncs.h
/usr/include/relion-1.3/src/time.h
/usr/include/relion-1.3/src/transformations.h