Coronation Street has revealed that Roy Cropper has seemingly reported Bobby Crawford for giving him a false alibi.

Bobby was arrested for perverting the course of justice in the latest instalment, but only after Roy had come clean about Bobby lying in his police statement.

Tuesday’s (May 28) episode jumped back in time to examine the events of the Bank Holiday from a completely different perspective.

This episode mostly followed Carla and DS Swain, with their paths crossing after Carla turned up at the precinct to return the detective’s lost police badge.

When Carla asked if there was any progress on getting Roy out of prison, DS Swain sensed her hesitation and asked whether Bobby was having doubts about his testimony.

Viewers will remember that Bobby recently lied to the police, claiming he’d seen an intruder in Lauren’s flat that didn’t match Roy’s description. An inadvertent consequence of his false testimony was that police started considering Daniel Osbourne as a suspect since he’d offered Lauren private tutoring.

Related: Coronation Street‘s Bobby Crawford to be kicked out after Lauren discovery

Following DS Swain’s allegation, Carla shot back: “The only information I want to hear is that you realise you’ve messed up and are releasing Roy.”

DS Swain reminded Carla that there is a “litany of evidence” linking Roy to Lauren’s disappearance, so he wouldn’t be released any time soon.

Carla questioned whether DS Swain was truly focused on the case, since she’d overheard the detective arguing with her daughter on the phone.

“If you have a complaint about my work, there’s a procedure. Feel free,” DS Swain shot back.

As Carla turned to leave, the detective suggested she’d just undermined Bobby’s statement with her questions.

Later, DS Swain turned up at Roy’s Rolls to apologise to Carla for their harsh exchange at the precinct. She promised to update Carla and Bobby if there were any developments for Roy.

“If I speak to Roy, I’ll strongly suggest he accepts your support,” DS Swain promised.

Carla admitted to Swain she’d been on the outs with Roy, leading Bobby to accuse her of giving away their secret.

“I’m getting so sick and tired of your lip,” Carla shot back at her nephew.

Carla rushed off, but found DS Swain crying in her car after another argument with her daughter. The two women bonded as Swain opened up about moving out of her family home.

“It’s not divorce, it’s [her wife’s] bereavement,” she explained.

Related: Coronation Street‘s DS Swain daughter storyline to begin

Swain mentioned that her daughter has been acting out since her other mum died, having most recently thrown Swain’s late wife’s clothing into the skip before it could be taken to a charity shop.

Carla relayed some of her own experience from losing Liam years ago, as she assured DS Swain that time would help ease the grief.

Their discussion turned back to Carla’s row with Roy, with Carla trying to convince the detective that she’d simply said “the wrong thing” to upset him.

Over at Roy’s Rolls, Carla pleaded with Bobby to tell the truth now, as this whole matter has ruined her relationship with Roy.

Later, Carla got a visit at home from DS Swain, with the detective revealing she had evidence Bobby may have made a false police statement.

Bobby was arrested on suspicion of perverting the course of justice, before DS Swain warned she could take Carla in too for encouraging Bobby to mislead the police.

In his police interview, Bobby repeatedly gave “no comment” responses when questioned by DS Swain about the inconsistencies in his statement.

While Bobby was released under investigation, Carla was shocked to learn from DS Swain that Roy himself had accused her of convincing Bobby to lie.

Swain tried to get through to Carla by revealing that her last conversation with her late wife was an argument, where her partner — who was a trainee detective — had found an error in one of Swain’s investigations.

She said that Carla’s repeated suggestion that Roy is innocent means that the police have kept that possibility in mind, even when their investigation suggested otherwise.

“Being lied to, being given false information, just makes my job so much harder,” Swain told her.

Related: Coronation Street star Tina O’Brien explains Sarah’s dangerous decision over Nathan

Viewers also saw that a professional rivalry had been brewing between DS Swain and her colleague DS Kit Green, the long-lost son of Bernie Winter.

After catching Sarah Barlow planting some evidence against evil abuser Nathan Curtis, DS Green turned up anyway to search Nathan’s van.

It didn’t long for DS Green to find a packet of USB drives hidden in the glove compartment, which violated his parole. Nathan was then arrested for the potential parole breach.