John Stephen Green, 66, was sentenced to life imprisonment, with a minimum term of 14 years, by a judge at Preston Crown Court today after a jury found him guilty of murder.
The emaciated pensioner weighed just six stone when she died in her own faeces on May 18.
Sentencing Green to life behind bars, with a minimum term of 14 years, Judge Mark Brown said: “You attempted to explain the death as being due to old age and you would have got away with the crime but for the vigilance of the coroner’s officer.”
He added: “There is no doubt in my mind that during the last few weeks of her life Bernadette was severely neglected.
“The only explanation for such neglect is that you hoped to hasten her decline and perhaps death by it.
"It seems you did what you could to prevent other people from seeing her and took no positive steps to ensure she received proper medical treatment.
“Eventually you decided to smother her.
“I am satisfied this was not a mercy killing and nor was it a killing in a moment of frustration or despair.
“Your mother was a good age but was entitled to live out her life to the full.
“You are a former police officer and it’s astonishing that such an individual with that background would have done what you did to his own mother.
“It’s said that a relationship between a mother and a son is normally a very deep one.
“There can only be one sentence for murder and its life imprisonment.”
When Green called emergency services the murder of his mother he convinced police and paramedics that Bernadette had died of old age.
However a coroner’s officer noticed that Bernadette’s medical records show that she had not seen a doctor since October 2013.
A post mortem revealed that Bernadette had been smothered and she had rotting black skin around her buttock area.
The court also heard how Green felt towards his mother in a series of text messages he sent to his daughter in which he described his devoutly Catholic mother as "it" and a "stinking corpse".