A "paranoid" man grabbed a knife and stabbed his brother to death after being confronted in the kitchen about a prank he had played on him.
Gilvy Anderson, 59, had been "deliberately antagonising" his brother by moving the angle of a CCTV camera Emile had installed to cover his shed.
He then knifed him as their mother Marlene watched TV in another room at their home in Stretford, Greater Manchester.
Gilvy was found guilty of manslaughter but not guilty of murder by a jury at Manchester Crown Court today.
Admitting he had moved the camera, he said: "He wound me up. It was childish but I did it every other day. I thought it was funny at the time."
After 50-year-old Emile challenged him over the prank, Gilvy picked up a knife and stabbed him in the chest, the Manchester Evening News reports.
He claimed he was acting in self defence after Emile had started 'growling' and came at him.
The court heard Gilvy had developed a "hatred" for Emile. The pair lived with another brother, Gerrard, 59, and their mother on Davyhulme Road.
Tensions had been high in the house for a while, and Gilvy became increasingly "distanced and paranoid", jurors were told.
He lost his job and had become interested in conspiracy theories, and covered electrical items such as TVs with a towel believing there may be cameras inside watching him. Gilvy believed his younger brother was stealing from him, and he also began antagonising Emile.
This included using a broomstick to move the angle of a CCTV camera which Emile had installed to cover his shed in the back yard. He also kept weapons in the house and had threatened to attack his brother, prosecutor Nick Johnson QC said.
Mrs Anderson, who had been watching TV in a sitting room, heard Emile utter a "loud cry" on Friday, April 16 last year. He had been stabbed by Gilvy after Emile had gone to confront him in the kitchen about moving the camera.
Gilvy claimed he was acting in self defence, after Emile started whispering "I'm sick of you, I'm sick of you", began "growling" and looked "psychotic".
Emile was able to walk back upstairs to his bedroom after being stabbed, but collapsed and was found unconscious in his room. Mrs Anderson told Gilvy to "get out", and said she feared her son may attack her after he armed himself with a bread knife. He put the knife down and went outside before the police arrived.
"One cannot begin to imagine what a difficult position Marlene Anderson is in, and we suggest she did her best to tell the truth as she saw it, despite such tragic circumstances," Mr Johnson said.
Gilvy will be sentenced later this month.
