  We present a combined experimental and computational study of the (110)
cross-sectional surface of Mn $\delta$-doped GaAs samples. We focus our study
on three different selected Mn defect configurations not previously studied in
details, namely surface interstitial Mn, isolated and in pairs, and
substitutional Mn atoms on cationic sites (Mn$_{\rm Ga}$) in the first
subsurface layer. The sensitivity of the STM images to the specific local
environment allows to distinguish between Mn interstitials with nearest
neighbor As atoms (Int$_{\rm As}$) rather than Ga atoms (Int$_{\rm Ga}$), and
to identify the fingerprint of peculiar satellite features around subsurface
substitutional Mn. The simulated STM maps for Int$_{\rm As}$, both isolated and
in pairs, and Mn$_{\rm Ga}$ in the first subsurface layer are consistent with
some experimental images hitherto not fully characterized.
