Observed Lyα spectra of LyC leakers from our Lyα criteria. Top: HST/COS Lyα profile of the known LyC leaking galaxy Haro 11 Bergvall et al. (2006), with a narrow P Cygni profile with v_peak ≤ 150 km s^-1, typical of Lyα transfer through low optical depth medium. Bottom: GHRS Lyα spectrum of a low-metallicity blue compact dwarf galaxy Tol 1214−277, highly suggestive of Lyman-continuum leakage from a riddled ISM (Sect. 2.3). The systemic redshifts and their errors (grey shaded area in each plot) were adopted from the 6dF survey for Haro 11 and from Pustilnik & Martin (2007) for Tol 1214−277. The blue horizontal line denotes the continuum level.