The police who helped make the Frank Foster murder mystery plot as realistic as possible have been sworn to secrecy by Coronation Street bosses.
Evil rapist Frank (played by Andrew Lancel) was found dead in his factory, and his girlfriend Sally, her ex-husband Kevin, his ex-fiancee Carla, her lover Peter and Carla's sister-in-law Michelle all became police suspects.
Viewers have all been wondering who is the murderer, but the Manchester CID already know, and have been sworn to secrecy, The Sun reports.
Soap bosses wanted the police questioning of the suspects to be as realistic as possible, and so handed the scripts over to the real life coppers for advice.
Greater Manchester Police helped to guide writers on police procedures, including making an arrest and carrying out interviews.
A Corrie spokesman said: "We always work closely with experts in any particular field to make sure our storylines are realistic."