A man who killed one of the UK’s wealthiest landowners and repeatedly stabbed his own mother told a psychiatrist that lockdown was a “full frontal” attack on his mental health, a court has heard. Thomas Schreiber said his mental health had deteriorated in the weeks before the knife attack on Sir Richard Sutton and Anne Schreiber because he was trapped living with the couple in their Dorset mansion. Giving evidence at Schreiber’s trial, the psychiatrist Dr Timothy Rogers said he believed the defendant had a history of major depressive disorder and alcohol misuse. It was also possible he may have had attention deficit hyperactivity disorder (ADHD), which can lead to impulsive actions. The psychiatrist said the defendant had struggled with low self-esteem since he was a teenager and was deeply affected by the “complete hell” of his parents’ separation. He could not come to terms with his mother setting up home with Sutton and felt his father, David, had been badly treated by the couple. Rogers said that because of the pandemic, pastimes he had used to maintain his wellbeing such as visiting art galleries or seeing friends were cut off and he was “locked into” an annexe at Sutton’s mansion “in the midst of all these family relationship problems”. The psychiatrist said: “He told me his mental health received a full frontal attack. He recalls feeling afraid to go downstairs. Things became mind-numbing. During lockdown he struggled with a number of depressive thoughts including feeling worthless, that his feelings didn’t matter, that everyone hated him.” Schreiber has told the jury at Winchester crown court that he snapped on the eighth anniversary of the death of his father, who had problems with alcohol. He claimed that just before the attack he was having a drink to mark the anniversary and was provoked by his mother supposedly telling him: “You’re drunk just like your father.” The defendant said a voice in his head shouted: “Attack, attack, attack.” Schreiber, 35, has admitted killing Sutton, 83, on 7 April but denies his murder and has pleaded not guilty to attempting to murder his mother, 66, who was left paralysed. Rogers said one particular thought that came back to Schreiber during lockdown was: “They don’t care about you, just like the didn’t care about Dad.” Schreiber visited a GP in March – about five weeks before the attack – and was prescribed antidepressants but did not take them. He is believed to have been three times the drink-drive limit at the time of the attack and has said he drank large gin and tonics that day while painting. Rogers said he had a “long history” of “heavy alcohol abuse” and a habit of drinking alone – but did not accept he was an alcoholic. The psychiatrist said he believed Schreiber’s depression could give him a partial defence of diminished responsibility but told the court he did not believe he was suffering from psychosis or experiencing hallucinations. A second psychiatrist, Dr John Sandford, described Schreiber as “a bit of a lost soul”, adding: “He didn’t think Sir Richard liked him, he felt Sir Richard adored his sisters Louisa and Rose but he was viewed as being work-shy and unable to achieve anything.” However, Sandford told the jury he did not believe Schreiber had amental disorder or a severe mental illness. The trial continues.