A man who stabbed his 71-year-old mother to death in their living room had paranoid delusions that everyone was “going to kill him”, a court has been told.

The jury heard that Shaun Emmerson, 51, inflicted fatal wounds on Christine Emmerson on August 3 last year in their shared home in Kirk Close, West Ashby, Lincolnshire, before climbing onto the roof and calling 999 to admit to carrying out a “violent attack” on her.

In Emmerson’s emergency call, which was played to the court, he was heard saying he “stabbed” his mother and thought she was dead.

He also told the call handler to send armed officers to the scene to “put me out of my misery” and claimed the “Department of Justice have been torturing me for the last 20 years”.

A trial of the facts at Lincoln Crown Court was told on Tuesday that Emmerson thought he could hear his “neighbours through the walls” who were saying they wanted to kill him in a “painful” way and he was afraid that someone would “attack” him in his sleep.

Emmerson is charged with murder but has been deemed unfit to stand trial due to a mental disability and did not enter a plea or appear in the dock.

Opening the case, prosecutor Christopher Donnellan KC told the jury that “extensive” blood was found with Mrs Emmerson’s body after she received 26 sharp force injuries to her head and neck and nine sharp force injuries to her torso.

He said: “The lifeless body of Christine Emmerson was found covered in blood, lying in a pool of blood near the fireplace in the living room.

“The Crown’s case is that what was said in that 999 call was reliable, and it was a reliable account because a person with delusional thoughts can say things accurately while suffering with delusions.”

Dr Stuart Hamilton, a forensic pathologist who carried out a post-mortem examination on Mrs Emmerson, said she would have “rapidly” lost consciousness from the injuries.

He said that stab wounds to her neck were the immediate cause of death.

A 23.5cm-long pink kitchen knife, which was shown to the court in a clear plastic case, was recovered from a bedroom in the house covered in a such large volume of blood that the weapon could not be DNA tested for who had held it, jurors were told.

Before the prosecution opened the case, Judge Simon Hirst explained to the jury that their role was to decide whether Emmerson did the acts alleged against him.

The judge told the jury: “The defendant is not fit to stand trial. Because of this there cannot be a trial in the usual way.

“You will not have to decide whether he is guilty, you will have to decide whether he did the act he is charged with.”

The trial continues.