The low energy electron (LEE) experiment, consisting of an array of 19 electrostatic analyzers, was conducted on board the polar orbiting satellite Atmosphere Explorer D (AE-D). Electron energy spectra and angular distributions obtained simultaneously with high temporal resolutions (~62 ms) have been used to study structures of inverted-V events. The principal results found are as follows: (1) Inverted-V events occur in the auroral as well as the polar cap latitudes. The low-latitude edge of the occurrence region varies from 62¿ near midnight to 80¿ invariant latitude at local noon. (2) The latitudinal width regularly observed is about 0.5¿ invariant latitude, and the longitudinal width can extend to at least 15¿ (3) The monoenergetic peak of the energy spectrum is found for pitch angles from 0¿ to 180¿ minus the local loss cone. (4) The temperature of precipitating electrons is linearly proportional to the peak energy. (5) The flux is field aligned at the peak energy and trapped above the peak energy. Immediately below the peak energy, the pitch angle distribution is V-shaped, peaking toward both small and large pitch angles. At energies further below the peak energy the distribution function becomes isotropics. (6) Fast irregular flux fluctuations are frequently observed at energies below the monoenergetic peak. These fluxes produce a secondary monoenergetic peak in the spectrum. The occurrence map indicates that the inverted-V occurrence region is not limited to the particle trapping boundary. The origin of the inverted-V precipitating electrons appears to be in the plasma sheet and the neutral sheet. Most of the energy and pitch angle structures can be interpreted as electrons accelerated by an electrostatic field, while the V-shaped pitch angle distributions suggest that particles were trapped between an electric potential and their mirror points. However, the existence of the monoenergetic peak at pitch angles larger than about 25¿ cannot be explained simply by an electrostatic field. The structural details are compared with predictions of three existing theories of creating the electrostatic field, and the results are qualitatively consistent with the theory of anomalous resistivity.