  We have modelled the line ratios and the continuum spectral energy
distribution (SED) of the short gamma-ray burst GRB100628A host galaxy complex.
The results suggest that an active galactic nucleus (AGN) and a star-burst (SB)
coexist in Nicuesa Guelbenzu et al.'s 'galaxy C'. The AGN spectrum is explained
by a relatively strong flux. Two of the observed regions (blobs) are located in
the ISM, outside the AGN photoionization cones. The strongest Hb line flux
calculated by a SB dominated model was found in the tidal tail of galaxy C,
while the strongest Hb line flux calculated by an AGN dominated model was found
in the galaxy C bulk. O/H element abundances are near solar everywhere, while
N/H spans a factor of ~10. The radio data have different origins, thermal
bremsstrahlung and reprocessed radiation by dust. The infrared-optical
photometric data measured from Nicuesa Guelbenzu et al.'s 'galaxy D', located
outside the X-ray telescope (XRT) error circle, are reproduced by a black-body
flux at 3000 K. This flux may represent the radiation of the underlying old
star population observed throughout the SED in the infrared. AGNs in other SGRB
hosts are investigated.
