Silke Hartshorne-Jones, a 42-year-old solicitor, was shot by her husband, 52-year-old Peter, at close range with a double-barrelled shotgun at their Suffolk home on 3 May last year.
Hartshorne-Jones, a gun dealer, called police at 4.44am and his wife was pronounced dead in hospital at 6.42am.
He admitted at an earlier hearing to manslaughter by diminished responsibility, which Mrs Hartshorne-Jones’ brother, Dr Dirk Lutschewitz, appeared to suggest is not enough.
Dr Lutschewitz told Ipswich Crown Court on Thursday it “hit [the family] like a thunderbolt when we heard Peter would be sentenced for manslaughter rather than for murder”.
He said he had known the defendant for almost 12 years and described him as an “intelligent but also highly manipulative man” who he believes is “trying to make a fool of us all”.
Dr Lutschewitz described the killing as an “unspeakable betrayal”, adding that his father had previously been “proud of his son-in-law, had loved him almost as if he had been his own son”.
Mrs Hartshorne-Jones, a German national, moved to London in 2007 and married her husband in 2010.
Her father, Hartmut Lutschewitz, said in a statement read to the court by a police officer: “My daughter, only 42 years old and in the prime of her life, was cold-bloodedly killed by a cowardly murderer.”
He said the “saddest and darkest hour in my and my sons’ life” was attending Ipswich Hospital where his daughter lay dead.
“I feel a deep, nearly physical pain I never felt before,” he added.
Prosecutor Peter Gair previously told the court Hartshorne-Jones, who it recently emerged believed he had Covid-19 in the weeks leading up to the attack, got in touch with various care providers – including the ambulance service, A&E departments and private GPs – 26 times between 16 March and 27 April.
No cause for his symptoms was found, though, the prosecution counsel added.
Ms Hartshorne-Jones told a neighbour days before she died that her husband “was not good at all and she was finding it difficult”, the court heard.
Dr Lisa Wootton, a consultant forensic psychiatrist, said she believed the defendant was “suffering from a severe depressive episode with psychotic symptoms” at the time of the killing.
She said Hartshorne-Jones had a history of mental health issues and was prescribed antidepressants in as early as 1996.
“He had a lot of contact with his GP and specialists about his physical health throughout his life,” she told the court, adding he once admitted he “had been using cocaine for one year” in 1997.
The sentencing, which is in its second day, continues.
Additional reporting by PA