"We have set ourselves the task of understanding and proving how each person was poisoned, how and if this caused or contributed to their deaths and obviously who is responsible.
"To that end we are making good progress but it won't be until the very end of the criminal or coronial process that these questions will be properly answered.
"Ultimately our aim is to ensure justice for all victims.
"The sheer size and complexity of this investigation is reflected in the number of inquiries that we have done, those still to do and the specialism surrounding all medical evidence and the invaluable and necessary involvement of the various experts who are supporting and assisting us.
"I want to take the opportunity to thank all the staff at Stepping Hill.
"I know the past 12 months have been an extremely difficult and challenging time for them but they have offered us their full and unwavering support throughout.
"It is important to note that we continue to work with them regarding the safeguarding of patients and since we were alerted back in July last year no other products have been contaminated."
More top news
One London Marathon runner who helped an exhausted competitor said it was "worth it" to help his rival.
Frost free Sunday night but turning much colder during Monday
A man has been killed by thieves who ran him over in his own car after he confronted them outside his home, police said.