Abstract: Understanding the nature and properties of the sources of the reionization requires quantifying the escape fraction (f_esc) of the Lyman Continuum photons from the galaxies. The most straightforward method to measure f_esc is to detect LyC photons from galaxies directly. In recent years, several works have detected LyC sources from the nearby universe to redshift ∼4. However, the success rate of searches of LyC emitters at high redshift is still low. Here I will talk about our discovery of the Lyman continuum (LyC) emission from a galaxy, CDFS-6664, at z = 3.797 in a sample of Lyman break galaxies with detected [O III] emission lines. The photometric and spectroscopic data of this object enable us to make a detailed analysis of its ISM properties and sightline IGM transmission. We find that the unusually high IGM transmission of LyC photons in CDFS-6664 may be related to a foreground type-2 quasar, CDF-202, at z = 3.7, with a projected separation of 1.2 arcmin only. The quasar may have photoevaporated optically thick absorbers and enhance the transmission on the sightline of CDFS-6664.