The low-key police operation began shortly after 6am yesterday when detectives arrived at the flat above a darts shop on the busy A6 road out of Stockport. None of the neighbouring businesses was open and no one around to witness the woman being taken from the home she shared with her fiancé on suspicion of murder.
Throughout the day more police arrived, their unmarked cars parked opposite the flat, while up to 10 officers searched inside.
Rebecca Leighton, 27, known to friends as Becki, lived little more than a mile from the Stepping Hill hospital where she worked as a nurse and where 60 detectives are investigating the suspected murder of three patients through the deliberate introduction of insulin to saline solution.
There was astonishment among the community of business owners at the arrest of Ms Leighton, whom locals knew well. She had grown up and gone to school in the town and was regularly seen coming and going from shifts at the hospital. They said she appeared to love her job, even though she described it as "hard work".
On her Facebook page the Open University graduate describes her love of boxer dogs and partying. "Well what can i say, im a happy go lucky kinda gal, loves the wkend (if im not workin) and having a laugh with the people that i call freinds for a reason," she wrote.
Hamid Bayatpoor, 47, who runs the local convenience store, painted a similarly carefree picture of the young woman. A regular at his shop, she would buy bottles of rosé wine and cigarettes at the weekend when she dressed up to go out, he said.
"She was always laughing and smiling. I don't believe she could do anything like this," he said of the allegations against her. She had given him advice when he told her his daughter wanted to study medicine, he added.
Security remained tight at Stepping Hill hospital. Visitors to the premises were questioned by security guards on the gates and medical teams dispensed insulin in teams of two.
The Nursing and Midwifery Council confirmed that Ms Leighton had been arrested. Its chief executive, Professor Dickon Weir-Hughes said: "We have commenced fitness to practise proceedings with a view to suspending her from the register as quickly as possible."
Inquests have been opened and adjourned into the deaths of the three patients who died: Tracey Arden, 44, George Keep, 84, and Arnold Lancaster, 71.
A fourth person, a man in his 40s, is still critically ill after his blood sugar dropped unexpectedly.
Police believe as many as 14 patients may have been affected. Detectives indicated they would look at historic cases that might be linked once they had a suspect.
Greater Manchester Police said: "This morning, a 27-year-old woman was arrested on suspicion of murder. She remains in police custody for questioning. Inquiries are continuing."