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 \sim 6.2 of \tau _ { eff } < 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 .