Patricia O'Connor's son Richard faced away from his younger sister Louise as he told the Central Criminal Court how she "didn't want us to report it" when their mother disappeared in 2017.
He looked straight ahead toward the jury as he testified, for the prosecution, that his sister "wore the trousers" in her relationship with murder accused Kieran Greene, who was "something of a fool and a moron".
Nearby, Louise and her daughter Stephanie sat in the dock in courtroom number 13, where they are on trial with two others over Patricia's gruesome death in 2017.
Richard O'Connor is the only member of the family to be called to give evidence so far in the trial, now in its third week.
Mr Greene (34), then-partner of Louise, is charged with murdering Patricia, a grandmother-of seven.
Louise (41), her ex-partner Keith Johnston (43) and their daughter Stephanie O'Connor (22) are accused of impeding the investigation.
It is alleged Stephanie disguised herself as her grandmother after she died to make it look like she was still alive, while Louise agreed to this.
They all deny the charges.
Patricia (61) was allegedly murdered on May 29, 2017, at the house at Mountain View Park, Rathfarnham, she shared with family including Louise, Stephanie and Mr Greene.
Her remains were found scattered in the Dublin and Wicklow mountains between June 10 and 14 that year.
Mr O'Connor was asked to pull his microphone closer as he told the jury in a deep, soft-spoken voice about the "friction" at the family home, where he had not lived for years.
It stemmed from Louise and her family living there and "not keeping the usual upkeep of the house", he said.
His mother had retired from her hospital cleaning job and "was at home more often".
"There wasn't enough being done for the amount of them in the house," he said. "It put a strain on her constantly."
"I seen my Mam giving out, saying 'move your lazy arse', or tidying up after the kids," he added.
May 30 was his birthday and when he had no contact from his mother, he called Louise the next day.
"That is when she informed me that my Mam had left with a suitcase and run off somewhere after an argument," he said.
He was asked to describe his mother. "She was a straight shooter and if you were in the wrong, she would tell you you were in the wrong," he said.
He was "worried" and had "no idea" where she might be, he added.
On June 1, he went to the house and Louise, their father Gus O'Connor and Mr Greene were there.
Prosecutor Roisin Lacey asked if an agreement was reached that Patricia should be reported missing.
"I agreed with my father. Louise didn't want us to report it," he replied.
Mr Greene "didn't say a thing", he added.
On June 11, he said, he walked to the shops with Mr Greene and asked about his missing mother.
"There wasn't a budge out of him," he said.
He agreed with defence barrister Conor Devally SC that he had told gardaí that Mr Greene was "something of a fool and a moron".
He agreed Louise was "sharper" than Mr Greene, saying: "She would be cute enough, yeah.
"Louise wore the trousers, yeah," he added.
Cross-examined by Louise O'Connor's barrister Michael Bowman SC, he said Louise had told him: "There's no need to involve the guards."
"I said 'I don't care, I'm going down, even if I have to go down myself'."
It struck him as unusual, he said, and "my Mam wouldn't just run off for no reason".
He agreed he did not mention this in his Garda statement.
He told the jury Louise and her children moved back into the house after the Garda investigation but had since been evicted by his father, who decided to sell the property.
Asked by Garnet Orange SC, for Stephanie O'Connor, if he played any role in the eviction, Mr O'Connor said it was his father's decision.
"I would have said it's not right for someone to move a family into where my mother was murdered," he added.
The trial continues.