  Detectable flux is visible in the Ly-alpha and Ly-beta troughs of the highest
redshift ($z=6.42$) quasar found to date, SDSS J1148+5251. This has previously
been interpreted as continuum contamination from an interloper galaxy at
z=4.94. We examine the Ly-gamma trough of SDSS J1148+5251 and show that this
interpretation is untenable: the spectrum does not show the continuum break in
a z=4.94 galaxy expected from absorption by the intervening Ly-alpha forest.
Therefore, flux must be leaking through at least one of the troughs from the
quasar itself. Contrary to previous claims, the flux ratios in the Ly-alpha and
Ly-beta troughs are consistent with pure transmission. From the Ly-gamma
trough, we place an upper bound on the effective Ly-alpha optical depth at
z~6.2 of tau < 14.3 (2 sigma). This implies a highly ionized IGM along this
line of sight and significant cosmic variance in the transition toward complete
Gunn-Peterson absorption. Detailed study of the observed transmission features
will shed light on this era.
