The man convicted of killing children's author Helen Bailey in 2016 "didn't seem particularly distressed or anxious at all" following the death of his wife, a paramedic told a court.
Ian Stewart, 61, is on trial accused of the murder of 47-year-old Diane Stewart at their home in Bassingbourn, Cambridgeshire in 2010.
Paramedic Spencer North, who attended the scene on June 25, said he was let through the gate by Stewart and found Mrs Stewart in cardiac arrest in the back garden.
He told jurors at Huntingdon Crown Court that Stewart appeared "initially distracted, idly pacing".
Asked by prosecutor Stuart Trimmer QC how Stewart appeared "emotionally", Mr North replied that he "didn't seem particularly distressed or anxious at all".
Mr North said Stewart told him his wife suffered from epilepsy, and that he had found her unresponsive when he arrived back home.
The paramedic said there "didn't seem to be any effective CPR but we were told when he came out of the gate that he was just doing CPR".
He said: "Generally effective CPR causes trauma. You crush the ribs, they pop, they snap, the airway is normally open.
"Not everyone knows how to do it but that's what you normally see if effective CPR is commenced."
He said he saw none of those signs.
Mr North said he saw "blood-stained saliva" on Mrs Stewart's mouth.
"If there had been effective mouth-to-mouth, what would you expect to see?" asked Mr Trimmer.
"That would have been everywhere," Mr North said, adding that there were "no obvious injuries" to Mrs Stewart.
"From my professional experience, when you go to a death of a loved one or a family member (they) typically show a heightened emotional state, screaming, crying, upset," said Mr North.
"Everyone's emotional responses are different. In this particular case he appeared dissociative and was simply answering questions calmly."
An ambulance service form completed at the scene indicated the call time as 11.24am, the ambulance was on scene at 11.41am and death was pronounced at 12.02pm.
Police constable Matt Gardner said he attended and completed a coroner's report form as he did not assess the death to be suspicious.
Asked how Stewart was when he was with him, he said: "He answered my questions clearly, I wouldn't say distressed, distraught, but people act very differently under such circumstances."
He agreed that he ascertained that Stewart was the last person to see his wife alive, recording the time of that as 10.30am on June 25.
Stewart denies the murder of his wife. The trial continues.