Silent Witness season 25 episode 2 recap: the end of forensic science as we know it?

Tom served as Sam's unofficial security detail in Stockholm back in 2018 when she was working for the UN. She was asked to carry out the post-mortem on a politician who was murdered by the two assassins involved in this case.

But Sam is not the only person who shares a link with Tom. He's also Nikki Alexander's ex-husband.

• READ MORE: David Caves on Silent Witness at 25: "This show could go on forever"

The pair were expecting a child together but Nikki suffered a stillbirth, which caused the breakdown of their relationship.

Tom claimed that he had been framed and despite the evidence telling Nikki otherwise – "DNA doesn't lie" – she leaned towards believing his innocence – and was later proved correct.

A Russian woman called Sonia Karpov had been pulling the strings to avenge her dead brother Andrei. He was a colonel who was part of a Russian contingent responsible for interfering in Ukrainian elections. He had been beaten by Tom while being held in UN custody, which was deemed a great humiliation by Andrei. On his release, he quickly spiralled into a deep depression following the loss of his rank and began drinking heavily, before taking his own life.

Sonia wanted Tom to suffer, as her brother had, and put her plan into motion. Given that Tom had been fired from the UN on Jomo's orders for his violent conduct, Sonia ordered the assassins to kill Sam's husband to make it look like Tom was out for revenge.

But it was the home secretary who was killed after the plan went awry, with Jomo surviving the attack.

Another individual who was snuffed out in episode 2 was Dan Clemence, a journalist who had served in the army with Tom and was concerned about Unitas's funding and its suitability to run the passport scheme. He shared those doubts with Alice, who had the authority to press pause on the scheme at any moment.

The pair had met at university and it was Dan who was confirmed to be the father of her unborn baby.

Two weeks prior, the Unitas co-founders had attended a meeting with the Department of Health over concerns about the company's backers. According to Sam, any doubts had been cleared up there and them, with Alice on board with the passporting system, despite allegations that the money had been acquired from corrupt regimes which Jomo had been carrying out election work for.

• READ MORE: Meet the cast of Silent Witness

Tom also claimed that Sam and Jono were lining up a string of investors for Unitas while they were still working for the UN.

"Are they demanding their pound of flesh?" Nikki asked Sam during one exchange, a question that she didn't answer.

Dan was bludgeoned to death with an ashtray by the assassins, who then tried to pin the murder on Tom by planting his blood under Dan's fingernails, but CCTV at Dan's flat exposed the real villains.

Eventually, Sonia was brought in for questioning, but despite wire transfers linking her to the assassins, who had been shot dead by the police, Tom's name still hadn't been cleared.

"You found his DNA , detective," she said. "Case closed, right?"

Regardless of the CCTV and the financial link, that still wasn't enough to acquit Tom of the other shootings, including that of Jomo's PA Rosa Hernandez.

As a consequence of Sam and Jomo's connection to Tom, Number 10 special adviser Oscar Harris informed Sam that the prime minister had decided to immediately postpone the passporting programme. That leaves Sam in a precarious position given that Unitas's mystery financial backers are expecting sizeable returns on their investment.

The government also want to bring a new pathologist onboard given Nikki's links to Tom.

"How sure are you about Faulkner?" asked Sam.

"Unless someone's figured out how to fake DNA, we're very sure," he replied.

But seemingly, that's exactly what's happened.

At the beginning of episode 2, Tom once again told Nikki that she couldn't trust Sam. On the face of it, that was proved to be the case when the former head of the Lyell swiped one of the blood samples that Nikki had collected from the assassins' hotel room when her back was turned.

DNA fabrication – which allowed the assassins to tie Tom to the murders – would be "the end of forensic science as we know it", said a troubled-looking Nikki.

On leaving the Lyell, Sam made a phone call in which she asked to meet with the voice on the other end of the line.

Has she really turned to the dark side? Or is she in over her head following some clumsy decision-making regarding Unitas? Is Sam intending to use the blood sample for nefarious means? Or did she steal it to run some tests of her own?

Silent Witness season 25 episode 3 airs on Monday 30th May at 9pm on BBC One. Visit our TV Guide to discover what else you can watch, or find all the latest news on our Drama hub.

The latest issue of Radio Times magazine is on sale now – subscribe now and get the next 12 issues for only £1. For more from the biggest stars in TV, listen to the Radio Times podcast with Jane Garvey.