A man allegedly murdered his partner having earlier accused her of having an affair with one of his sons.

Colin Kennedy, 63, is charged with killing Catherine Stewart at their home in Airdrie on July 4 2021.

Prosecutors claim Kennedy repeatedly struck the 54-year-old on the head and body with a knife.

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He went on trial at the High Court in Glasgow where he denies the murder charge.

Jurors were told how Kennedy - nicknamed Coddy - had a total of seven children including two daughters and a son with Catherine.

One of those - Natalie Kennedy - gave evidence.

She described growing up in a "happy family" with no violence.

The 32-year-old was asked by prosecutor John McElroy KC how her parents relationship was in the run up to the alleged murder.

She did not live with them, but was in regular contact.

Natalie stated they had had a "fall out", had not been speaking and went to separate rooms in their home away from each other.

The witness said she went on to have concerns about Kennedy's mental health.

This included a claim that Catherine was having an affair with one of his sons - her step-son - who stayed in Liverpool.

Mr McElroy asked her: "What did you think?"

She replied: "I did not believe it."

Natalie went on to be asked about the morning of the alleged killing.

She had been at home getting ready for work, had opened the back door to let her dog out when she heard "screaming and shouting".

It was a girl she knew who she described as being "hysterical" shouting her name.

Natalie went on to learn her mother had been "stabbed".

She lived nearby and went to her parents home, but police had arrived by that time, so could not get access.

Kennedy's lawyer later questioned Natalie regarding the concerns about Kennedy's mental health and his claims about Catherine's alleged infidelity.

John Scullion KC stated: "Your father was telling people that he thought she was having an affair with your half-brother. Her step-son.

"When your father told you his thoughts - to put it bluntly - you believed it was ludicrous?"

Natalie said: "Yes."

Mr Scullion said: "You are aware it was not just you who was telling him it was ridiculous. Other people were.

"His view was completely fixed and unshakeable."

The witness replied: "It was as if what was in his mind was real."

The KC said: "You thought he was deluded?"

Natalie said: "I thought there was something mentally wrong."

The trial, before judge Lord Arthurson, continues.