Not so much that - although it does read like an espionage novel - I doubt he was murdered. It's the government rubbishing a man's reputation after 'outing' him, deliberately and openly to the point where he tops himself. All to save the an unelected spin doctor who is recognised as the power behind Blair's throne - Alastair Campbell.
They tried to bully the BBC into shutting up about the dossier - even threatening it's status regarding the license fee - and when they wouldn't play ball they went directly for the journalist and then the source.