A teenager has admitted killing his 89-year-old grandmother by setting fire to her house.
Retired university lecturer Vera Croghan, 89, died at her home in Norwich on December 11, 2020.
Her grandson Chanatorn Croghan was detained under the Mental Health Act hours later.
The 19-year-old admitted manslaughter by diminished responsibility on Thursday at Norwich Crown Court.
Croghan, of Northside in Norwich, also pleaded guilty to arson, having started a fire in his grandmother's home on December 11, 2020, the force said.
The defendant, who is also known as Marco, had been staying with his grandmother when police were called to the address at around midnight on December 10, 2020 following an argument between him and another man.
Police said that, on arrival, officers established that no offences had taken place.
Croghan stayed at his grandmother's house and the man left without his knowledge.
At around 6.30am, a member of the public saw smoke coming from the home and called the fire service.
Firefighters discovered a fire which had been smouldering for some time, then found Vera Croghan in an upstairs bedroom.
No-one else was inside the address at the time, police said.
Ms Croghan was pronounced dead at the scene and a Home Office post-mortem examination recorded that she died from smoke inhalation.
Croghan returned to the address at around 3.30pm on December 11 and was arrested then detained under the Mental Health Act.
He was charged with murder, attempted murder and arson.
Prosecutors accepted his guilty pleas to the charges of manslaughter by diminished responsibility, and arson.
He is due to be sentenced at Norwich Crown Court on April 14.
In a tribute released through police at the time of her death, Ms Croghan's family described her as a "much-loved mum of four and grandmother of 10".
"She was a well-known and highly respected academic, having been a lecturer in Swedish and Scandinavian Studies at the UEA from its establishment in 1963 until her retirement over 30 years later," her family said.
"She was the author of the best-selling 'Teach Yourself Swedish' book.
"She dearly loved Norwich and the local area, and she loved the house that she had lived in continuously for 57 years."
