Silent Witness recap: Who are the suspects? And what happened to Sally Vaughan?

Episode one introduced us to a few suspect individuals. There's David Cannon, Julian Rhind-Tutt's cocky pathologist who we, the viewers, saw having a heated argument with Sally at her home before she disappeared. He has a motive – she's refusing to sell her lab to him – and investigators can also pin him to her last known location after finding the remnants of a mug he smashed in her bin. It's why he's now stationed with Nikki and the gang so they can keep an eye on him.

We also know he's not being truthful about Gwen – the "lab technician" he told Nikki he was meeting at the pub. Ever the investigator, she already knows he's lying and also got eyes on a map of Sally's village he had received from this mysterious woman. Why does he have it in his possession? He certainly doesn't seem as innocent as DCI Bernhardt assumes.

Then there's the mysterious Gary Hadlow, loan shark and bouncer with a record for GBH and last seen lurking (below) during Livtar's fundraiser. Later in the episode he was seen discussing Livtar's death after a romp with a mystery woman named Anna Madeley. "Do you think it's our fault?" she asked him. "Probably" came the reply. We know a note was found in Livtar's possessions that read "I can make you disappear and get away with it" and that Gary and he had exchanged calls. Are these two the senders of that threatening message?

If they are, perhaps it's connected with the unmarked grave found by investigators just before the credits rolled. Livtar had left flowers at the abandoned location moments before his death – and Gary knew where it was. But what was most intriguing about the bones was the rectangular-like structure uncovered by Jack, a shape that we saw matched the masks worn by those creepy figures in the woods at the start of the episode.

Then there's Angus Merrick. Sally did a post-mortem on his brother, a procedure Merrick was keen to prevent taking place. Her phone was traced to his property by police and once located there, it was found covered in her blood. "I don't know any Sally," he told police. Given the weight of evidence against him, it's not surprising they don't believe him.

Emma Singh, Livtar's widow, also seemed to know more than she was letting on. Called to the police station after it became clear her husband's death was suspicious, she revealed she had overheard Gary telling Livtar: "it's one thing asking for money for yourself but asking for it for her is something else?" Who is the mysterious "her"? If there's 'another woman' it might give Emma a motive to bump off her husband? Or was she telling the truth when she said she never got a chance to question him about it?

And there's one more thing we noticed: at the start of the episode, when Sally was still in situ, we saw her in her office on the phone. She was speaking to a man in a suit, telling him that Melissa Loel "needs to be looked over top to bottom". Presumably it's a post mortem being discussed – and we would have dismissed it as idle conversation had the man on the end of the phone not been pictured on the screen looking more than a little shifty. Who is Melissa Loel and how does she fit into the story? Is she the woman Livtar was seeing?

Silent Witness continues on Tuesday 9th January at 9pm on BBC1

What did you think of episode one? Let us know below: