Charges have been dropped against a nurse accused of contaminating saline at Stockport's Stepping Hill Hospital.
Rebecca Leighton, 27, of Heaviley, was arrested by police investigating the deaths of several patients in July.
Greater Manchester Police have revealed they are investigating 40 cases of contamination including seven deaths.
Prosecutors said there had not been "sufficient evidence" for whether the case could go ahead. Miss Leighton said she had been "living in hell".
A worrying outcome of this investigation, I've been watching with some interest and when they arrested this nurse it hit the headlines and I did wonder how she would manage if she was found to be innocent.
I see the NMC suspended her for 18 months in August, and they have issued this statement
The NMC is aware of the developments today in the case of Rebecca Leighton, and her release without criminal charge.
The interim order suspending Ms Leighton from the NMC's register, which was imposed on 2 August 2011, will remain in place at present. We will continue to liaise with Stockport NHS Foundation Trust to carry out our own investigations, and establish whether further action needs to be taken.
It will be interesting to see how this develops. I sincerely hope that catch whoever is responsible for this appalling act that harmed so many vulnerable people