A father on trial for allegedly murdering his infant son told the High Court in Pretoria on Wednesday that he had assaulted the baby's mother, but would never hurt his child.

Nolan Schoeman, 32, and his common-law-wife, Marissa Rudman, 36, are on trial for allegedly murdering their two-month-old son Wade in April 2009, and assaulting another child.

Wade died of head injuries several days after he was admitted to the Steve Biko Hospital, in Pretoria, in a critical condition.

Schoeman admitted assaulting Rudman and even breaking her nose, but said he had finally hit her back after being repeatedly assaulted by her.

After Wade's death, he said they had a “huge fight” during which she accused him of assaulting the baby.

Afterwards they made up and mutually decided that neither was responsible.

Instead, Schoeman blamed a friend who had moved in with them shortly before the baby's death.

Despite this suspicion, he did not confront the man or tell the police of his suspicions.

Schoeman admitted that he and Rudman had used drugs with the man and that they had allowed him to carry on living with them after their arrest for the murder.

He said he had a “hazy memory”, which he blamed on his drug use.

He denied that it was possible that he could have assaulted Wade while drugged and not remember.

“I know in my heart I would never do that,” he said.

Asked about a time he allegedly hit a child on the back with a ball and then shoved a plant into his mouth until he vomited, Schoeman said he “was just joking” and that “everyone was laughing”.

Schoeman and Rudman have both pleaded not guilty to murder and two charges of child abuse.

Judge Cynthia Pretorius postponed their trial to May 15 so that Rudman could obtain a paediatrician to testify on her behalf. - Sapa