Warning! This article contains major spoilers.
Or did they?
All might not be as it seems with the bent copper’s death, which came at the climax of Sunday night’s episode.
Viewers of the hit BBC cop show saw AC-12 uncover evidence that suggested Thurwell – played by James Nesbitt – was the “Unknown User” who had been speaking to DCI Jo Davidson on the internet chat service, and who’d ordered DI Kate Fleming’s murder.
After discovering his location, AC-12 worked with Spanish police to carry out a raid on his property in Spain, where he had been living since going on the run.
But while at the address, officers found a male and female dead at the property, which we were led to believe was Thurwell.
However, there is some evidence to suggest he might actually be alive.
Firstly, the live footage from the bodycam was grainy to say the least, and we also never actually saw a face – could it be that Thurwell was in collusion with someone in the Spanish police to stage his own death?
There’s also the small matter of how James Nesbitt’s appearance in Line Of Duty leaked in the first place.
You’ll remember that earlier this month, The Sun reported that a “top actor” was joining the show after the BBC Maestro website accidentally posted two scenes featuring the star in question.
The paper described how the face of a well-known actor “could be seen on a database being searched by DI Steve Arnott”, while another “short scene in which the character appears was also shown”.
Assuming James was the only “top actor” The Sun was talking about, we’ve yet to see him actually appear in the show, as so far, his character has only been seen in pictures and mugshots.
Therefore, it would suggest there’s at least one scene we’ve yet to see that features James as Marcus Thurwell.
Of course, there’s the possibility that the scene on the BBC Maestro website was a plant from Line Of Duty bosses to throw us off the scent, in which case there are going to be some questions about how Thurwell has ended up dead.
Still, dead or alive, Thurwell is likely to play a key part in next Sunday’s final episode, with the net looking like it is closing in on Chief Constable Philip Osborne.
Line Of Duty concludes on Sunday at 9pm on BBC One.