  We present a versatile imaging scheme for fermionic $^6$Li atoms with
single-particle sensitivity. Our method works for freely propagating particles
and completely eliminates the need for confining potentials during the imaging
process. We illuminate individual atoms in free space with resonant light and
collect their fluorescence on an electron-multiplying CCD camera using a
high-numerical-aperture imaging system. We detect approximately \num{20}
photons per atom during an exposure of 20 $\mu$s and identify individual atoms
with a fidelity of $99.4\pm0.3$ % . By addressing different optical transitions
during two exposures in rapid succession, we additionally resolve the hyperfine
spin state of each particle. The position uncertainty of the imaging scheme is
4.0 $\mu$m, given by the diffusive motion of the particles during the imaging
pulse. The absence of confining potentials enables readout procedures, such as
the measurement of single-particle momenta in time of flight, which we
demonstrate here. Our imaging scheme is technically simple and easily adapted
to other atomic species.
