Line of Duty fans were left confused after episode six aired on Sunday evening and have wasted no time in coming up with an intriguing theory to explain what's going on. Warning – major spoilers for episode six ahead!
Towards the end of the episode, AC-12 were following Spanish authorities after they had tracked down Marcus Thurwell (James Nesbitt) at his residence abroad.
Via night cameras, the crew entered the former detective's home but found two dead bodies in a room, one man and one woman, with a Spanish AFO stating it was Marcus' body.
WATCH: HELLO! breaks down Line of Duty episode six
However, plenty of fans took to social media to share their disbelief that Marcus would be dead already without making an appearance in person – particularly with actor James Nesbitt playing him.
One person tweeted: "Thurwell is not dead, there's no way James Nesbitt has been brought in as just a mug shot." Another echoed this, writing: "There is no way Marcus Thurwell is dead. You don't bring in James Nesbitt to not have him appear once on screen. My hunch is that he was who Davidson believed was her father. She daren’t look at his photo during her interrogation #LineOfDuty."
A third commented: "Marcus Thurwell is 100% who Jo Davidson thought was her dad. Also, don't think he's really dead. #LineOfDuty."
Line of Duty's episode six provided another action packed hour
Another went even further to say that the AFO confirming Marcus' body looked a little familiar: "#LineofDuty theory: That supposed police gunman that 'found' Thurwell dead in Spain looks a fair bit like Jimmy Nesbit..."
Marcus Thurwell is a former senior detective who was uncovered by AC-12 as being the Senior Investigating Officer in the Oliver Stephens-Lloyd case – an investigation into child sexual abuse at Sands View Boys Home (think series three and Danny Waldron).
In addition, his name was also mentioned in relation to the 2003 case of Lawrence Christopher, who was attacked by racist thugs and died in police custody. Is Marcus really dead? And could he be the elusive fourth man? We'll have to wait for next week's final to find out more…
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