A man who stabbed his housemate four times in the back, then went shopping for alcohol, has been found guilty of murder.

Mark Carpenter, 57, of Embankment Road, Plymouth, was convicted of murdering Harry Jackson by a jury at Plymouth Crown Court today.

Police were called to their shared house at 8.22pm on 4 May 2026, after another resident found Harry’s body at the bottom of the stairs.  

A post-mortem examination found that he had been stabbed four times in the back and had defensive injuries to his left wrist.

Helen Phillips of the Crown Prosecution Service said: “Carpenter claimed that he acted in self-defence when he repeatedly stabbed Harry, but the evidence told another story.  

"Instead of calling for help, over the next five hours, CCTV showed him visiting shops to buy alcohol, with bloodstains still visible on his clothing.

"Having heard all the evidence, the jury convicted Carpenter of murder. Our thoughts are with Harry’s family and friends as they come to terms with this tragic loss.”

Building the case

Carpenter’s claims of self-defence were disproved by CCTV footage, witness accounts, activity on his mobile phone, and forensic analysis of the scene.

Carpenter claimed Harry had assaulted him twice before he stabbed him in self-defence. The post-mortem examination found that Harry had been stabbed four times in the back. Defensive injuries to his wrist and hand had been inflicted as Harry tried to defend himself from Carpenter’s knife blows.  

On the evening of the attack, Carpenter told several people different accounts of what had happened. He told one friend that he had been in a fight. In a call to another woman, he said "so I got revenge" and described stabbing his neighbour in the back. He also told her he would spend the rest of his life in prison.

When police interviewed Carpenter, he answered "no comment" to every question and in prepared statements, he said he had been attacked by Harry and might have stabbed him accidentally.

In court, he accepted he had stabbed Harry but claimed he acted in self-defence and did not intend to cause serious harm. The jury rejected this.

Evidence presented by prosecutors disproved Carpenter’s claims of self-defence, including the fact cleaning items found outside his room, as well as discarded clothes, were stained with Harry’s blood.

DNA evidence was also retrieved from the handle of the knife used to attack Harry.