A 42-year-old man killed himself hours after he stabbed his father to death on the doorstep of his parents' home in Kingsteignton.
Owen Chandler was caught on a ring doorbell camera seconds before he stabbed his father Peter Freeman to death - but the victim had not recognised the hooded figure.
The day after the murder, Chandler was found dead in his locked car in a remote car park on the Devon coast.
Coroner Ian Arrow recorded a suicide conclusion on 42 year old Chandler who died from a stab wound to his right arm and the toxic effects of a prescribed drug overdose of 100 anti-histamine tablets.
Mr Arrow said Chandler had been under the care of the mental health services until he was discharged in November 2018 but said there had only been limited assessment of the risk he posed to himself and others.
An inquest earlier this week into his father Peter Freeman's death, heard Chandler wanted revenge and to torture his parents but the main deterrent had been getting caught.
Mr Freeman, 73, suffered fatal chest and neck wounds in the attack as he answered his front door in Chockland Road on the evening of Sunday June 9, 2019.
Det Sgt Dan Ritson told the hearing at Plymouth Coroner's Court that police received a 999 call at 21.21pm from the victim's wife Linda saying a stranger had gone to their home in Kingsteignton, Devon, and rang the doorbell as the couple watched TV.
DS Ritson said the killer, later identified as their son, asked if someone called Johnson lived at the bungalow or nearby and retired businessman Mr Freeman replied no.
He said Chandler then pulled out a 17.5cm bladed Bowie style knife and attacked Mr Freeman before his wife locked the door and called police.
The inquest heard the doorbell footage showed a man wearing a blue Lonsdale hoodie carrying a bag for life approach the house and within two minutes he closed the door and made off.
DS Ritson said:"The male was unrecognisable to the Freeman family, a stranger who was not known at that time."
The next day Chandler was discovered dead in a car at nearby Labrador Bay car park in Shaldon, Devon, and his description matched the man in the doorbell images.
Blood on his jumper also matched Mr Freeman's DNA and a bag for life and a blood stained knife were found.
A suicide letter addressed to the coroner was found in the glove box which made clear references to the attack the night before.
The inquest heard that Mr Freeman died from chest and neck stab wounds which led to a huge blood loss.
The coroner Ian Arrow was told that Chandler had been under the care of mental health services since his teenage years and was discharged in November 2018.
A report said Chandler suffered with emotional unstable personality and PTSD and had a history of self-harm and tried to kill himself before.
The inquest heard Chandler say he wanted revenge on his parents and to torture them.
It was a long term preoccupation where he wanted to kill his parents and then himself because he had 'nothing to lose'.