Complex sentence: Because of his conviction, his parents' estate passed to the cousins who had found the silencer in the gun cupboard after the murders, with the flecks of blood and paint that proved pivotal to the prosecution.
Split into simpler sentences: Because of his conviction, his parents' estate passed to his cousins. It was one of these cousins who found the silencer in the gun cupboard after the murders, with the flecks of blood and paint that proved pivotal to the prosecution.