In a framework of classical dynamics we develop a new classification scheme for multi-electron trajectories in terms of sequences of binary electron collisions. The Wannier threshold law σ ∝ E^α for four-body break-up of Lithium is confirmed and it is shown that α deviates experimentally due to its determination between 2-5 eV above threshold. For the angular distribution of the ionized electrons we do not find a preferential symmetric break-up with an inter-electronic angle of 120 degree as predicted by Wannier's theory. However, the angular pattern is consistent with an analysis in terms of binary collisions. Our results are expected to hold generally for three-electron dynamics.