Complex sentence: Drew was also responsible for the murders of Dr Stone, the original Newsboy Legion and the alien known as Dubbilex, he also attempted to murder Daily Planet photojournalist Jimmy Olsen, who had accidentally uncovered the conspiracy.
Split into simpler sentences: Drew was also responsible for the murders of Dr Stone, the original Newsboy Legion and the alien known as Dubbilex. He also attempted to murder Daily Planet photojournalist Jimmy Olsen, who had accidentally uncovered the conspiracy.