A particle is moving in 3D space, under a potential

$$V = -\frac{\alpha}{r}-\frac{\vec{r} \cdot \vec{\mu}}{r^3 } $$

where $\vec{\mu}$ is some constant vector. I need to show there are three conserved quantities. By writing the Lagrangian or Hamiltonian in spherical co-ordinates, it is evident that energy and angular momentum are conserved. But where is the third conserved quantity? Any guidance would be appreciated.