Cardiff Crown Court in south Wales heard that toddler Elsi Scully-Hicks died in May 2016 after suffering a fractured skull while being violently shaken, two weeks after being formally adopted by defendant Matthew Scully-Hicks and his husband.
The toddler sustained bruises, a broken leg and fell down a flight of stairs during the eight months that she was in the care of the 31-year-old fitness instructor.
Scully-Hicks told the court that he was unable to handle the pressures of bringing up the child, calling her "a psycho" and "Satan dressed up in a Babygro" in text messages.
Jurors unanimously found him guilty of murder following a four-week trial.
"There must have been gripping and shaking. Either her head was hit against a hard surface, or a hard object was used to strike Elsie to the head," he added.
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