A woman died five weeks after bowel surgery in which there was a series of errors, an inquest has heard.
Susan Warby, 57, died at the West Suffolk Hospital in Bury St Edmunds on 30 August, 2018.
An inquest into her death heard her family were sent an anonymous letter highlighting mistakes made during her treatment.
Both Suffolk Police and the hospital launched investigations into the source at the request of the coroner.
The court was told Mrs Warby, who was diagnosed with a digestive condition in 1997, had collapsed at home with abdominal pain on 26 July.
She underwent emergency open surgery for a perforated bowel the following day.
A statement from her husband Jon Warby said a "rampant infection" was also putting a strain on her kidneys.
He said he was told that during her operation, an arterial line was fitted with an intravenous infusion to keep it clear - but that Mrs Warby had been incorrectly given glucose instead of saline.
"I asked what the effect of this could be and the consultant told me brain damage or death," he told Suffolk's senior coroner Nigel Parsley.
He said his wife's condition was "up and down" in the following days, and she suffered a punctured lung during a further operation to replace the arterial line.
Mr Warby said he was concerned the "tricky procedure" was carried out by a junior member of staff, rather than an experienced consultant.
His wife contracted a fungal infection a week later and the family agreed to withdraw active treatment.
Her cause of death was recorded as multi-organ failure, with contributory causes including septicaemia and pneumonia.
The inquest continues.
Correction: Wednesday 16 January 2020 : An earlier version of this story wrongly stated the inquest was told there was a "witch hunt to identify a whistleblower". This has now been removed.