Assuming that leptons heavier than muons exist in nature, we consider their decay modes and the correlations between the decay products of l+ and l- in the colliding-beam experiment: e++e--->l++l-. Far above the threshold, the helicities of l+ and l- tend to be opposite to each other. Near the threshold the directions of spins of l+ and l- prefer to be parallel to each other, and the sum of the two spins prefers to be either parallel or anti-parallel to the direction of the incident electron. Because the parity conservation is violated maximally in the decays of l+ and l-, the angular distributions of decay products depend strongly on the spin orientation of the heavy leptons. Since the spins of l+ and l- are strongly correlated in the production, we found a strong correlation between the energy-angle distributions of the decay products of l+ and l-. The decay widths of l- into channels νlν̄ee-, νlν̄μμ-, νlπ-, νlK-, νlρ-, νlK*, νlA1, νlQ, and νl+hadron continuum as functions of the mass of l- are estimated.