Police today started a criminal investigation into the death of hospital blunder mum Teresa Innes.

The 38-year-old died at the weekend after medical staff were given permission to stop artificially feeding her.

The former care worker went into a coma in September 2001 after staff at Bradford Royal Infirmary administered penicillin during a minor operation to an infected insect bite, despite her being acutely allergic to the drug.

Medical chiefs have already admitted it was an "error", causing Teresa to suffer a massive heart attack which starved her brain of oxygen.

Detectives are now investigating the circumstances surrounding the tragedy and will question staff responsible for her welfare.

Their inquiry will examine the possibility of criminal negligence on the hospital's part and even whether Teresa's death was due to a deliberate act.

Her death on Saturday was reported to Bradford Coroner Roger Whittaker. After examining the facts surrounding the tragedy, he handed over the case for detectives to investigate.

A West Yorkshire Police spokesman said: "The matter has been referred to West Yorkshire Police by HM Coroners for investigation.

"Police inquiries are ongoing and we are liaising with Bradford Teaching Hospitals NHS Trust."

Today a spokesman for the Trust said: "Everyone connected with Teresa's care is deeply saddened by her death and our sympathies are very much with her family and friends at this sad time.

"It was very much the overriding wish of her family, those responsible for her nursing and medical care, and the Courts, that she was allowed to end her life peacefully and with dignity. These wishes were met."

He added: "We have expressed our deepest regret to the family for the tragic events that happened in September 2001. Although an extremely rare occurrence, it is one from which we - and the wider NHS - are determined to learn so that we reduce the risk of it happening again to an absolute minimum."

He said that since the tragedy "every effort" had been made to ensure she was comfortable.

"Her family and friends have been an important part of her care in hospital and we value their support and understanding as we have worked together in the best interests of Teresa. We are grateful to them for the way they have helped and supported the team that have been caring for her.

"The past few weeks have been a particularly difficult and sad time for staff - they too share the family's grief over the loss of Teresa."

Specialist counsellors have been arranged to comfort Teresa's family and friends as well as BRI staff, said the Trust spokesman.

Teresa, of Ternhill Grove, Bradford, a mum of a teenage son, initially sought treatment at the BRI for a leg ulcer triggered by an insect bite.

Her allergic reaction to the penicillin put her into a coma from which she never regained consciousness.

Last month one of the country's top judges ruled she had no chance of recovering from the "twilight world" she inhabited and there was nothing the medical profession could do to help her.

Dame Elizabeth Butler-Sloss, head of the High Court Family Division, agreed Teresa had been in a "permanent vegetative state" for at least 15 months and gave medical staff permission to stop feeding her through a tube.

At the time of the decision to let her die, Christopher Johnson, representing Bradford Hospitals NHS Trust, recounted a statement from Teresa's son Scott, 18.

It read: "My mother was a lively person who I know would not wish to be kept alive in this condition."

Solicitors have been appointed by Teresa's family to consider legal action against the Trust. Her family insist medical staff had been warned about her penicillin allergy when she was admitted to hospital.