DC Holker assisted DI Mannery with the investigation into the murder of Maxine Peacock and the brutal assault on Emily Bishop in January 2003, both crimes committed by Richard Hillman although no one knew this at the time.
Holker, along with Mannery, conducted a wholly unsympathetic interrogation of a grief-stricken Ashley Peacock, insinuating that he had a drink problem and, stating that he was no oil painting, asking blatantly if Ashley had paid money for a beautiful woman like Maxine to marry him. Holker asked if Maxine had anyone else on the side. Ashley’s solicitor, Kathleen Fearn, demanded a break from the questioning but Mannery initially refused. When a break did occur, Mannery returned to say that Ashley was being released as an important development had occurred (Aidan Critchley, set up by Richard, had been found squatting in the vacant hardware shop on Victoria Street and arrested with items from the Peacocks' house in his possession, all planted by Hillman). Ashley bitterly asked how Mannery and Holker could sleep at night. The latter replied that they wouldn’t catch Maxine’s killer by being nice.
In November of the same year, Holker and another colleague called to 12 Coronation Street to speak with Steve and Karen McDonald after Steve’s father Jim absconded from Holmes Gate Prison on day release from where he had been serving a sentence for manslaughter imposed three years before. Jim hid in the cavity under the hot water boiler in the airing cupboard while Holker asked Steve if he had seen his father. Steve commented that the flat was the last place he was bound to make for but the policemen insisted on searching the property. They failed to find Jim and Steve and Karen were able to get him to Blackpool where he was desperate to see wife Liz who he suspected was having an affair with her boss Laurie Dyson in The Black Dog pub where she worked.