In this paper we present computational results of the flow past a cylinder oscillating transversely and in-line to a uniform stream. The in-line oscillation has a frequency equal to twice the transverse frequency. The cylinder thus follows an eight-like trajectory, emulating the response of real structures undergoing vortex-induced vibrations. Here, the transverse oscillation frequency obtains values close to the natural frequency of the Kármán vortex street, while the corresponding oscillation amplitude is varied from zero to 0.6 times the cylinder diameter. We find that certain combinations of oscillation frequency and amplitude result in chaotic wakes, characterized by chaotic lift spectra. We attribute the chaotic flow behavior to the presence of cylinder oscillation in the in-line direction, which forces a symmetric mode; the competition between this mode and the staggered Kármán mode induces the observed chaotic states.