Complex sentence: Steven Grover was found to be trolling websites that have posted pro-CIW positions and opinions; under an assumed screen name, Grover posted several comments disparaging the ethics and honesty of the leadership of the group.
Split into simpler sentences: Steven Grover was found to be trolling websites that have posted pro-CIW positions and opinions. Under an assumed screen name, Grover posted several comments disparaging the ethics and honesty of the leadership of the group.