Bulk stable (alpha-FeSi2, beta-FeSi2) and epitaxially stabilized (gamma-FeSi2, Fe0.5Si which has the CsCl structure and 50% Fe vacancies) phases with the stoichiometry Fe:Si = 1:2 grown on Si(111) by molecular beam epitaxy have been studied by Fe-57 conversion electron Mossbauer spectroscopy. The Mossbauer parameters are discussed with respect to the local surrounding of the Fe atoms. From the angular dependence of the line intensities in the case of beta-FeS2 the hitherto accepted interpretation of the spectra in terms of quadrupole coupling of the lines is discarded. Information about the defect (Fe vacancies) distributions in Fe0.5Si and alpha-FeSi2 obtained from the population fractions of the different sites are reported. The possible nature of the observed spectrum for the gamma-FeSi2 phase is also discussed.