A "trusted member" of Patricia O'Connor's family, who carried out repairs on the bathroom where she was allegedly murdered, told gardai: "I know it looks bad."
Handyman Keith Johnston (43), who did the work in the days after Ms O'Connor was first reported missing, said he was "trying to help the family" so she would not "chuck them out" when she returned.
Mr Johnston, who is accused of carrying out refurbishments to conceal or destroy murder evidence, denied he was "up to something" when he was arrested and interviewed.
The Central Criminal Court has heard Mr Johnston is the ex-partner of Patricia O'Connor's daughter Louise (41).
He is one of four people on trial over the death of Patricia O'Connor in 2017.
Louise's then-partner Kieran Greene (34), is charged with murder, while Mr Johnston, Louise and her daughter Stephanie O'Connor (22) are accused of impeding the investigation.
The charges against Mr Johnston allege that he also assisted Mr Greene in buying implements for use in the concealment of Ms O'Connor's remains.
The four have all pleaded not guilty.
Ms O'Connor, a grandmother-of-seven, 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.
The jury heard Mr Johnston was arrested on September 26, 2017, and taken to Bray Garda Station for interview.
He told gardai that when he was at the house on the day Patricia was reported missing - June 1 - he noticed a wooden step in the bathroom had gone soft and he "put down a few tiles".
He was not asked to do the work and did it over a few days, he said.
He went with Mr Greene to get supplies and got tiles, wood and grout.
He took his own hacksaw from home, he said.
Mr Johnston told gardai he had done other work in the house and "don't just say I did one thing to make it look like I was up to something because that is not the case".
"I know it looks bad but that is just the way it is," he said.
"Hand on heart, that was trying to help the family, like, so they wouldn't get chucked out."
He told gardai he felt "sickened" after Mr Greene "confessed" that he had killed Patricia.
Earlier, Stephanie O'Connor identified herself as a person seen on CCTV coming in the back door of her house with a "suitcase-type bag" on the night her grandmother was allegedly murdered.
However, she told gardai she did not kill her "nanny", or assist anyone in her killing.
Stephanie, who is accused of disguising herself as her grandmother to pretend she was still alive on May 29, was initially arrested on suspicion of murder, on September 2, 2017.
In interview, gardai showed her CCTV footage of the outside of the house on the night of the alleged murder.
She was shown a clip of someone coming in the back door with a bag at 10.05pm and asked what she saw.
"Someone going inside, me I guess," she said.
"I'm bringing a bag from the shed."
She said she went to get the bag after being asked by her mother, Louise.
It was just stuff from the shed and she then went to bed, she said.
The jury previously heard Stephanie and Louise both told gardai the last time they saw Patricia was when she stormed out of the house after a row that night.
Louise is accused of agreeing to Stephanie disguising herself as Patricia O'Connor.
The trial continues.