Complex sentence: Matthew is convinced that Rosemary is behind the false alibis and doesn't think much of them, Hari is also in trouble when Louise finds out he is lying and runs her car off the road to stop her telling the police.
Split into simpler sentences: Matthew is convinced that Rosemary is behind the false alibis and doesn't think much of them. Hari was also in trouble when Louise found out he was lying and ran her car off the road to stop her telling the police.