  We study real resonances and embedded eigenvalues of the
Kramers--Fokker--Planck operator with a long-range potential. We prove that
thresholds are only possible accumulation points of eigenvalues and that the
limiting absorption principle holds true for energies outside an exceptional
set. We also prove that the eigenfunctions associated with discrete eigenvalues
decay exponentially and those associated with embedded non-threshold ones decay
polynomially.
