  The Z-burst model and the direct propagation of UHE proton in negligible
extragalactic magnetic fields produce gamma-rays afterglows and precursors
halos, respectively at GeVs and TeV energy band a few degree around the UHECR
arrival direction. The possible correlation of UHECR clusters (doublet,
triplet) with nearby BL Lac sources at E_p = 4*10^19 eV offer a test for this
necessary Gamma-UHECR trace. We estimate the secondary gamma energy and spectra
and we suggest how to disentangle between the different scenarios. We show why
Z-Burst model is still the most realistic model to explain UHECR behaviour and
their correlation to known BL Lac sources.
