  Context: A detailed study of the close interacting binary V4142\,Sgr based on
photometric and spectroscopic analysis is presented.This system belongs to the
enigmatic class of Algol-like variables showing a long photometric cycle of
unknown nature. Aims: Performing photometric data-mining and spectroscopic
observations covering the orbital cycle, we obtain the orbital parameters and
the stellar properties of the binary system, along with the physical properties
of the accretion disk located around the hot star. Insights on the evolutive
path of the system are obtained. Methods: The light curve was modeled through
an inverse modeling method using a theoretical light curve of the binary
system, considering the light curve contribution of both stars and the
accretion disk of the hot star to obtain the fundamental parameters. To
constrain the main stellar parameters the mass ratio was fixed, as well as the
donor temperature using the obtained values from our spectroscopic analysis
including deblending methods to isolate the spectral lines of the stellar
components. The system parameters were compared with a grid of binary star
evolutive models in order to get insights on the evolutionary history of the
system. Results: The orbital period and the long cycle were re-calculated and
found to be of $30.633 \pm 0.002 ~\mathrm{days}$ and $1201 \pm 14
~\mathrm{days}$. The spectral analysis reveals H$\alpha$ double emission with a
persistent $V \leq R$ asymmetry which is considered evidence of a possible wind
emergin from the hotspot region...
