Lucas a Murderer?

Whom would you take with you, if you had to ship drugs from Dakar to Hamburg?
Exactly! Not someone with a white vest and clean conscience, but someone without scruples and prepared to do everything necessary.

In my defense of Lucas I overlooked that and tended to make Vaughan the seducer of John Bateman. But is this assumption right?

John Bateman left Maya behind in England and went to deliver drugs.
I would take a murderer with me, should I ever want to undertake such an outrageous endeavor. A murderer would have nothing to lose and much to gain.
John even mentions towards Harry, that he had done bad things back in England before Dakar. But neither Harry nor I listened overly attentive.
Also Maya says that now she understands John completely, defining him as a murderer. She does explicitly not differentiate between now and 15 years prior.

Also Vaughan astonished me by going down so easily. As a really bad character I expected him to make much more fuss and fight harder. But what he does is protecting Maya from the Chinese and accepting his death, because calling an ambulance would have endangered Maya.
So in the end is Vaughan good and Lucas/John through and through bad?
But what should I make now of the characterization Harry Pearce gave us about Vaughan? His end statement on the roof clearly gives Vaughan a leading role in corrupting John Bateman?
Lucas / John a murderer, who just had forgotten his true self for a while and became a hero spy?

Contradictions everywhere! So what should I think in the end? – I tend to defend John Bateman, who was able to enact a nice and clever spy for MI-5 and could fool all who came in contact with him as well as me.