  We re-analyze the precision radial velocity (RV) observations of HD160691 (mu
Ara) by the Anglo-Australian Planet Search Team. The star is supposed to host
two Jovian companions (HD160691b, HD160691c) in long-period orbits about 630
days and about 2500 days, respectively) and a hot-Neptune (HD160691d) in about
9 days orbit. We perform a global search for the best fits in the orbital
parameters space with a hybrid code employing the genetic algorithm and simplex
method. The stability of Keplerian fits is verified with the N-body model of
the RV signal that takes into account the dynamical constraints (so called GAMP
method). Our analysis reveals a signature of the fourth, yet unconfirmed,
Jupiter-like planet HD160691e in about 307 days orbit. Overall, the global
architecture of four-planet configuration recalls the Solar system. All
companions of mu Ara move in quasi-circular orbits. The orbits of two inner
Jovian planets are close to the 2:1 mean motion resonance. The alternative
three-planet system involves two Jovian planets in eccentric orbits (e about
0.3), close to the 4:1 MMR, but it yields a significantly worse fit to the
data. We also verify a hypothesis of the 1:1 MMR in the subsystem of two inner
Jovian planets in the four-planet model.
