A husband on trial for the murder of his wife more than 10 years after she died seemed "aloof" and "totally unbothered" at her funeral, a court has heard.
Diane Stewart, 47, died at the home she shared with Ian Stewart in Bassingbourn, Cambridgeshire, in 2010.
At the time, the cause of her death was recorded as sudden unexplained death in epilepsy (SUDEP).
But police decided to investigate the case after a jury found Stewart, 61, guilty in 2017 of murdering his fiancee, children's author Helen Bailey, the year before.
Alexandra Bailey, an old friend who had known Mrs Stewart since they attended Salford University together in the 1980s, said in a statement read at Huntingdon Crown Court that Mrs Stewart's death was a "complete shock".
"When Diane died it was a complete shock to me, it was so unexpected," she said.
In the statement read by prosecution barrister Neil King, Ms Bailey said that she attended Mrs Stewart's funeral.
"I do recall Ian's behaviour at the funeral appeared a little odd," she said. "He seemed totally unbothered and seemed quite aloof."
She went on: "I didn't know if he was behaving this way for the boys but I just didn't feel it was right."
During questioning by prosecutor Stuart Trimmer QC, Home Office pathologist Dr Nat Cary told the court he would "expect to see injuries"on the outside of the body of someone falling to a concrete surface during a fit.
Mr Trimmer said: "We know no such injuries were found on the body of Diane Stewart.
"There was no tongue biting and it appears, although the conclusion is perhaps not as secure as it might be, that there was no loss of urine."
Dr Cary agreed that there were no injuries identified, and no evidence of natural disease.
Mr Trimmer asked: "In terms of what may have killed her, do you have views?"
Dr Cary replied: "Yes. One contender that needs to be considered is a syndrome called SUDEP - it's really a diagnosis of exclusion and an equal diagnosis of exclusion is having been put into such a state by some covert means.
"Smothering or interfering with the mechanics of breathing or some kind of drug use."
Mr Trimmer said that the "only kind of drug screen done after death was in relation to the anti-epileptic drug" taken by Mrs Stewart.
Dr Cary agreed that full toxicology was not done as part of the 2010 post-mortem examination.
The pathologist said that "sometimes in fatal neck compression, signs are pretty subtle".
He said that a neck dissection is "not a part of a routine autopsy".
Mr Trimmer said that Dr Cary was the pathologist who "dealt with Helen Bailey", whose body had been "in a cesspit for three months".
Dr Cary said there was "no injury that was visible" on Ms Bailey, and "there was no natural disease that was apparent".
Mr Trimmer said that Ms Bailey's "consciousness had been reduced by administration of a drug", and Dr Cary agreed that this was sleeping tablets.
Questioned by Mr Trimmer, Dr Cary described ways that the airway could be obstructed, including by an armlock.
"An armlock, if administered carefully, you can cap somebody's neck in the crook of the elbow," Dr Cary said.
"It used to be used by law enforcement agencies around the world as it was a so-called sleeper hold and could result in loss of consciousness in seconds.
"It compresses the carotid arteries on either side of the neck and prevents blood getting to the brain."
Dr Cary agreed with Amjad Malik QC, defending, that SUDEP was a "possible factor in the death of Diane Stewart" but added that "on the background of cases of SUDEP it becomes very unlikely".
Stewart denies the murder of his wife.
The trial continues.