The evolution of radiation-induced carbon-oxygen related defects with the fluence of MeV electrons and upon subsequent isochronal annealing (75-350 °C) in Si crystals with different carbon and oxygen content has been studied by means of Local Vibrational Mode (LVM) spectroscopy. In particular, the generation kinetics of the bands at 998 and 991 cm^-1 is considered and additional arguments supporting their previous assignment to the I₂C_iO_i and I₃C_iO_i complexes are found. An annealing behaviour of the LVMs related to the C4 (IC_iO_i) defect has been studied in the various Si crystals irradiated with different particles. In all the samples studied the bands at 940 and 1024 cm^-1 are found to disappear at about 200 °C while three new LVM bands, at 724 cm^-1 (O-related) and at 952 and 973 cm^-1 (both C-related) are emerging. Further increase in annealing temperature up to 250-275 °C results in a transformation of the latter bands into another set of LVM bands at 969 cm^-1 (O-related) and at 951 and 977 cm^-1 (both C-related). These bands disappear upon annealing in the temperature range 300-325 °C. The ratios of all the bands intensities as well as their transformation rates do not depend on the oxygen and carbon content in the Si samples nor on the kind of irradiation (2.5 and 10 MeV electrons, fast neutrons) and irradiation doses. These facts confirm our previous conclusion that all the above-mentioned LVMs arise from the C4 defect being in different configurations (IC_iO_i, IC_iO_i*, and IC_iO_i**).