-Devon & Cornwall, UK. -May 26, 2021. This video shows the moment a man was arrested for murder - after he brutally killed his own grandmother. Cameron Dancey-Stevenson, 27, was given a life sentence with a minimum of 18 years behind bars and being found guilty of murdering Alison Stevenson, 62. Dancey-Stevenson, originally from Helston but who has for some time resided at Langdon Psychiatric Hospital in Dawlish, denied killing his grandmother at her house overnight between May 24 and 25, 2021. But he was convicted at Exeter Crown Court on Tuesday by a jury following a very brief period of deliberation. Now Devon and Cornwall Police have released video footage of the moment the killer was arrested. The startling footage shows armed police officers pointing an automatic assault rifle at him and shouting to get down and show his hands. They are then seen swooping on the murderer and continue shouting as they put him in handcuffs and place him under arrest. A further video clip ominously shows his walking near her grandmother's home on the day he took her life. He stabbed her to death later that night. Sentencing Dancey-Stevenson, Judge Simon Carr said: "Your victim was your grandmother who was at the time 62 years old. She was a much loved grandmother, daughter, sister and friend." Judge Carr spoke of how Dancey-Stevenson's behaviour became concerning in his late teens and early 20s and how a restraining order was made in 2017 after he assaulted his mother and grandmother. Judge Carr added: "During this time Alison never stopped loving you and caring for you." Judge Carr detailed how Ms Stevenson, due to her love for her grandson, initiated contact again with him. He said: "She knew it was in breach of the restraining order but would not stand by and do nothing, such was the generosity of her character." After Dancey-Stevenson was released from prison, his behaviour became more worrying and Ms Stevenson asked him to stay away. Despite this on May 17 he was found in her garden with a friend and she called the police. He was awaiting sentence for this offence - breaching the restraining order - at the time of the murder Judge Carr said: "It is clear from the evidence regarding a call with your father that you were angry with Alison and blamed her." He then detailed how on the night in question Dancey-Stevenson broke in through an insecure kitchen window, armed himself with a knife and went upstairs and attacked his grandmother while she slept. Judge Carr added: "After you had killed her you remained in the house for a number of hours, washing your clothes and trying to remove forensic evidence." Judge Carr noted Dancey-Stevenson's complex mental health background before passing a life sentence with a minimum of 18 years. He is likely to remain at Langdon until he's well enough to be transferred to the general prison population. Ms Stevenson was killed by her grandson while he was the subject of a restraining order preventing him from contacting her or going to her property which he had already breached and was awaiting sentencing for. Dancey-Stevenson had made threats towards his grandmother during a call with his dad as he was mad she had given a statement to police. Despite the restraining order Ms Stevenson continued to try to help her grandson, such was her care towards him On the night of the murder Dancey-Stevenson broke into his grandmother's house overnight through an insecure window and stabbed her frantically in her own bed. He then fled before later being arrested after a time sleeping rough in a tent in the woods, where he had stayed on and off for months. During the opening, prosecuting barrister Tahir Khan, KC, told the jury that Dancey-Stevenson had made threats to his grandmother before and was said to be angry she had given a statement to the police. After her death, Dancey-Stevenson's DNA was found on the washing machine and tumble drier, his fingerprints were found under the bannister of the stairs, and his footprint was found in blood near Ms Stevenson's bedroom. A knife was found in the sink with Ms Stevenson's blood on it. Dancey-Stevenson claimed he was in the house at the time but that somebody else broke in and killed Ms Stevenson. Mr Khan pointed out that nothing was stolen and no DNA of anybody else was found in the house or nearby. He added that if this was true Dancey-Stevenson would have had plenty of time to call the police. He entered through an insecure kitchen window that only family members knew about. At the sentencing hearing a statement was read on behalf of Marina Stevenson, Ms Stevenson's daughter and Dancey-Stevenson's aunt, who spoke on behalf of the whole family. She said: "My grandfather is having to cope with the loss of his daughter, not by illness but in such a cruel way when he should be living his later years peacefully. The brutality of the attack shocked him and all of us to the core.