DS Grant DS Grant ( formerly a Detective Constable ) and her colleague DS Nash were assigned to investigating the murder of Frank Foster in March 2012 . The two detectives began their inquiries by questioning Sally Webster , who had found Frank ' s lifeless body with a bloody head wound on the factory floor of Underworld . When Sally proclaimed her innocence and mentioned that others had greater motives to murder the businessman , they went on to question Carla Connor . Carla admitted to having had a showdown with Frank shortly before his death ( which almost resulted in him raping her a second time ) , but also denied murdering him and claimed to have managed to escape before things could turn violent . Peter Barlow had gone on a drunken binge the night Frank was murdered , and his state when he returned the following morning clearly put him in the frame for the murder . He and Carla agreed to maintain to the police that he had returned to 9a Rosamund Street from a party at Nick ' s Bistro and stayed there all night . Peter was taken to Weatherfield Police Station for questioning by Nash and Grant after it was reported that he ' d made drunken threats in the bistro to kill Frank . When his story was turned over with evidence that his credit card was used to purchase alcohol later in the evening , Peter admitted he was out all night and had no recollection of anything . However , he was released without charge . Nash arrested Carla when a contract which signed Underworld over to Frank was discovered to be missing . Carla ' s fingerprints were also found on the whisky bottle which was believed to have killed Frank . Despite a police search of her flat , the contract was not found , and she was released on bail . Peter assumed that Carla was guilty and made a false confession in order to protect her . Peter ' s fraudulent confession was eventually exposed , and following that Frank ' s mother Anne was discovered to have been the culprit and was taken into custody . By January 2016 she had been promoted to Detective Sergeant , and led the investigation into a failed attempt of robbery at Nick ' s Bistro and the injuries sustained to Carla as she was thrown from the assailants ' getaway car as she tried to retrieve her stolen handbag . The bistro ' s staff were questioned regarding the incident and after discovering that the power cut on the night in question had knocked out the CCTV cameras , a search of the premises also turned up Tracy Barlow ' s mobile phone in the bistro ' s kitchen . The police then called at 1 Coronation Street to question Tracy , and although she explained that she ' d gone over to the bistro to surprise chef Robert Preston but discovered that nobody was there , Grant had a hunch that Tracy was withholding information . Grant next went to Weatherfield General in order to question Carla who was now out of danger . Although unable to provide any significant information , Carla remembered that one of the robbers mentioned waitress Steph Britton by name . Calling back at the bistro , Grant reinterviewed Steph - who confirmed that the only person that she could think of who ' d hold a grudge against her was ex - boyfriend Jamie Bowman , who had been recently released on police bail following a charge of disclosing private and sexual images with intent to cause distress . Returning to the hospital to speak with Carla once more , Grant confirmed that Jamie Bowman had been arrested and readily admitted to the robbery . List of appearances . 2012 2016