A 30-year-old father admitted he sat and cried after "an incident" with his three-month-old daughter.
The Christchurch District Court jury in the trial of Christopher Dean Matthews today viewed his video interviews with police investigating how the baby was injured.
The child, Caitlyn, suffered brain damage from whatthe Crown says was a case of shaken baby syndrome.
Matthews denies a representative charge of causing the baby grievous bodily harm with reckless disregard for safety.
Breaking down several times, Matthews told the interviewing detective sergeant that during one morning when he was looking after Caitlyn she had been grizzly and would not settle.
He spoke of the pressure of coping through a period when she had been ill with croup and chicken pox. The officer described him in the interview as "a person with a short fuse".
That morning he had tried to calm her down and "then the incident happened".
He acknowledged on the video "by words and gestures" that he had held and shaken her.
"The head moved backwards."
"As soon as I realised what was happening, I felt so sick," he said.
"I put her back to bed. I sat down beside her and I was just crying. I just thought, `What have I done?' I just gave her a hug and expressed that I didn't mean it."
Police were told by medical staff that the injuries were equivalent to not less than a baby falling from a two-storey window or being in a car accident at speed.
Matthews said in a later interview that two other instances "reported by his partner" of him shaking the baby at night when he was very tired "could have been him simply him losing his grip when he was holding the child."
The trial before Judge Phil Moran and a jury is scheduled to take five days.
Kerryn Beaton is crown prosecutor and Garry Collin is defence counsel.
