The father of a man who stalked and killed a former colleague before taking his own life said his son had gone "downhill" after being sacked for harassing women.
Michael Sellers became "obsessed" with 23-year-old Gracie Spinks after she told him she did not want a relationship with him.
He was dismissed by Derbyshire e-commerce firm Xbite, where they worked together, after she made a complaint about him.
An internal investigation by the company found he had behaved inappropriately towards eight other women.
Sellers stabbed Gracie to death at Blue Lodge Farm, Duckmanton, near Chesterfield, Derbyshire, on 18 June in 2021. His body was found a short distance away.
Following the conclusion of an inquest into Gracie's death, a separate inquest was held into Sellers' death on Monday, 20 November.
A coroner ruled that he took his own life.
In a statement read out at Chesterfield Coroner's Court, Sellers’ father, Stephen Sellers, said his son "just shut down and really went downhill" after losing his job at Xbite, but would not discuss the reason for the dismissal.
He said: "He was so upset. He was blindsided. I don’t think he knew what he had done wrong."
Mr Sellers also said that his son had told his family: "I don’t want her (Spinks) to love me, I just want her to like me."
In a statement, Pc Daniel Ball, of Derbyshire Constabulary, said Sellers' family, who were not present at the inquest, described him as "dying inside" after losing his job.
He added: “After Xbite, Michael’s personality changed. He was fragile, very quiet and withdrawn, seemingly having lost his way in life."
Coroner Matthew Kewley said Sellers "carefully planned" his actions after becoming "utterly obsessed" with Gracie.
He said: "This was not a spur-of-the-moment act of violence.
“Michael Sellers engaged in significant planning and preparation in the weeks leading up to the murder.
“His actions were premeditated and carefully planned.
“He effectively removed himself from any form of accountability for his actions towards Gracie Spinks.
“I am certain that he died by suicide.”
The inquest into Sellers’ death took place after a jury concluded on Thursday that he had unlawfully killed Ms Spinks by stabbing her 10 times.
Derbyshire Constabulary admitted numerous failings in the case, including how police handled a complaint Gracie made about his behaviour in January 2021.
Five months later the force was contacted about a bag of weapons found near Blue Lodge Farm, but treated them as lost property.
Giving evidence on Monday, Det Con Denise Sandall, of Derbyshire Constabulary, said bank statements showed Sellers had bought the knives found in the bag on March 11 2021.
He then purchased more knives the same day that the bag was discovered, which were then found at the scene on the day of the killing.
Det Con Sandall said: "It did seem that he had made a plan about what he intended to do and he seemed quite certain that this was what he wanted to do."
A black holdall, which Sellers was seen on CCTV placing into his car hours before his death, was found near his body, and a suicide note was later found in a bedside drawer.
The officer said Sellers was born in Sheffield, lived with his family, and "did not appear to have any close friends and he had never had a girlfriend".
In his conclusion, Mr Kewley said Sellers was “incapable of understanding how to behave towards his female colleagues” and “lacked even a shred of insight into his own behaviour”.