The family of a woman who died after eating a Pret flatbread fear that items were not kept or properly analysed.
Celia Marsh, 42, suffered an allergic reaction to the super-veg rainbow wrap which contained yoghurt that was supposed to be dairy-free.
Dental nurse and mum-of-five Celia was out having a meal with her family when she had a fatal anaphylactic reaction at the branch in Bath, Somerset.
The £3.75 vegan snack contained a dairy-free yoghurt which was found to contain traces of milk protein following the tragedy in December 2017.
Legal action was taken against Pret, and the food supplier Planet Coconut, by Bath and North East Somerset Council, but charges were dropped last year.
Celia's husband Andy Marsh has since launched a personal injury lawsuit at London's High Court to seek answers about what happened.
But the family's legal representative outlined some of their concerns at the final pre-inquest hearing into her death, before Avon coroner Maria Voisin.
He said: "We are very keen that the inquest does not divert into an investigation into an investigation. It is about how the deceased came about their death.
"But there are clearly concerns with the investigation and that forms part of the context and background, which we will be exploring with the experts."
The lawyer said it was "deeply regrettable" that "contents were not kept and properly analysed" and he described testing as "inadequate."
"It has caused both the family and others great concern," he added.
In the largely administrative two hour hearing today, the coroner also ruled the full inquest will take place without a jury at Ashton Gate, in Bristol, and will not have remote access facilities.
It was also deemed it was necessary to obtain a statement from the director of CoYo, which was described as the "missing link" in the chain, to probe to what extent the risk of milk contamination in the product was passed on.
The flatbread contained a coconut milk yoghurt alternative supplied by company CoYo, that was supposed to be dairy free. These branded yoghurts are made by Planet Coconut.
Coroner Maria Voisin added: "We will request a statement but it is going to be very limited. We are not asking him to go above and and beyond that one area of concern."
She said this would be the last pre inquest hearing ahead of the full inquest listed for three weeks and due to take place from September 6.
In a statement released today, Pret a Manger said it would fully cooperate with the hearing.
A spokesperson said: "Our deepest sympathies remain with the Marsh family over their terrible loss and we are doing everything we can to support this inquest.
"Following Celia Marsh's death in 2017, charges were brought against Pret. The prosecution ended due to the lack of evidence and as a result, Pret was found not guilty.
"Over the past few years, Pret has established an industry-leading approach to helping customers with allergies, through the Pret Allergy Plan.
"We will continue to do everything we can to make sure that every customer has the information they need to make the right choice for them."
In a previous statement, Celia's family said: "We have kept a dignified silence as the family has come to terms with her sudden and unexpected death.
"Celia was a much-loved mother, daughter, sister and wife. We miss her greatly and just want answers to why she died after lunch with her family."
Her death came after Natasha Ednan-Laperouse, 15, died in 2016 after eating a Pret baguette bought at Heathrow Airport.
She had a nut allergy.
A full hearing is expected to take place next month.
