Published: Monday 29 March 2021 at 10:00 p.m.

Unforgettable Season 4, Episode 6 dealt a devastating blow to viewers when DCI Cassie Stewart (played by Nicola Walker in the cast Unforgotten), the beloved cop and co-lead of the series, was hospitalized after a car accident

After Cassie left, Sunny was forced to continue the historic homicide investigation into the death of Matthew Walsh, whose headless and handless remains were found frozen earlier in the season

The four unforgotten suspects – Fiona Grayson, Elizabeth “Liz” Baildon, Dean Barton and Ram Sidhu – were once prospective copper workers in the 1990s

They were all present the night Matthew Walsh died in a parcel and they all worked together to hide the body But which one killed it?

Matthew Walsh died in the 1990s after tripping in a parcel and knocking himself out – before the killer found Walsh and pushed a metal foundation spring through his head wound

Some of the suspects had had direct contact with Walsh a few weeks before his disappearance: he had sexually assaulted Fiona and beat up Ram. Liz had a relationship with Fiona and could have murdered Walsh to avenge her friend

However, it emerged that another suspect had a connection with Walsh Dean (the seedy businessman who made mysterious trips to Calais) had changed his own name from Quinn to Barton to reflect his connection to his career criminal family disguise

His supportive older brother Stephen had encouraged Dean’s ambitions beyond crime more, even giving him an engraved fountain pen, however, he was murdered by a rival gang member: none other than Matthew Walsh

Sunny connected after an earlier tip from Cassie when she suggested they investigate how Dean’s brother died

The theory came together when the team tracked down the maker of the pen, who checked the purchase records and found it had been bought by Stephen and engraved with Dean’s initials as a birthday present

Dean always seemed to be the most good-natured and personable of the four suspects – he’d turned out to be a “gracious” interviewee when Cassie spoke to him on episode three

As he told her back then, you never really know what someone is capable of

The father-to-be and the copper-ram serving will likely face jail sentences for not only having been accused of preventing a legal burial of a corpse (like Liz and Fiona), but also being involved in Dean’s cocaine smuggling

Bank records indicate that Dean had paid him large sums of money in exchange for bribing a customs officer (who had also been arrested and had shown himself to be very cooperative)

Meanwhile, Fiona faces the additional fee of practicing as a therapist with a fake license (she had never applied for a real one as she wanted to hide her historically dangerous driving beliefs) Despite everything, her husband forgave her

After all, after almost 30 years (similar to Cassie), Liz had to retire from the police force and may face jail time for hiding Matthew Walsh’s body

She was popular when we first met her (newly engaged and ready for the top police job in the East Anglia area) but her future and relationship are uncertain by the end of episode six

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Unforgotten, unforgotten series 4

World News – GB – Unforgotten end of series 4 declared: Who killed Matthew Walsh?