A nurse forged a prescription and tried to murder her elderly mother using a lethal dose of insulin, a court heard today.

Julia Knight denies attempting to murder Irene Robson while she was recovering from a fall at the Horton General Hospital.

John Price, prosecuting, told a jury of five women and seven men today that 56-year-old Knight had been working at the West Bar GP surgery in Banbury at the time.

Mr Price said computer records showed that on the morning of Tuesday, October 7, Knight had researched different types on insulin on her work computer.

He added that she then sneaked into a colleague's room while they were making the morning teas and coffees and forged a repeat prescription for insulin in the name of a current patient, which she collected at around 12.35pm that day at a Sainsbury's pharmacy.

Mr Price said she then visited her 81-year-old mum and used a self-administering pen to poison her.

The jury at Oxford Crown Court heard that Knight had left the ward, but Ms Robson's long-term partner noticed something was wrong and raised the alarm.

Mr Price said Ms Robson had lost consciousness and began foaming at the mouth, but doctors and nurses managed to stabilise her.

However, Mr Price added that the  insulin caused Ms Robson's health to "roller coaster" for about 36 hours before she was finally stabilised.

Knight, of Sycamore Drive, Banbury, admits giving her mum the insulin but denies attempted murder and causing grievous bodily harm with intent.

Mr Price told the court that Knight knew insulin was lethal to non-diabetics because she had used it to try to commit suicide in 2006 after hearing it caused a "painless death".

Judge Ian Pringle told the jury that Ms Robson had died last month.

But he warned them that her death had "no bearing whatsoever" on the issues they were being asked to decide and not to speculate on it.

The trial continues.