The jury in the trial of the Chinese Businessman Anxiang Du at Northampton Crown Court has been hearing from a forensic psychiatrist.
Mr Du is accused of killing all four members of the Ding family at their home in Wooton on April 29 2011.
Professor Nigel Eastman was called as a witness by Defence Barrister Rebecca Trowler QC.
He said he had attempted to establish whether a defence of diminished responsibility or loss of self control would be available to Mr Du.
During four visits to interview Mr Du in prison Professor Eastman said he had spoken about his life prior to the killing of Jeff and Helen Ding and their two daughters.
At the start of the first of those interviews Professor Eastman said Mr Du had accepted that he had killed the four members of the family.
Mr Du had suffered depression on several occasions, including during a long running legal dispute with the Dings which was ongoing for more than ten years.
He admitted that he struggled to show his emotions and that although he rarely lost his temper there were occasions when he would lash out when tormented as a child and teenager.
He also described an incident involving his wife when he threatened her with a knife as she questioned whether they should continue with their legal dispute. He said he'd waved a knife at her a couple of times and become angry but had regretted it after. He described it as wholly out of character.
The jury of eight women and four men will be asked to decide whether Mr Du was suffering from an abnormality of mental function arising from a recognised medical condition.
They will also decide whether it affected rational judgement or self control and whether the medical condition provided an explanation for his actions and whether it was a significant factor in the lead up to the killings.
Mr Du does not dispute that he killed the family however he denies Murder.
The case continues.