Gardaí are now treating as murder the disappearance of 45-year-old Tina Satchwell from her home in Youghal, Co Cork, in March 2017.
A man in his 50s has been arrested on suspicion of murder.
He has been taken to a garda station in Cork for questioning.
A garda team is also searching a premises in Youghal.
Ms Satchwell was reported missing by her husband, Richard, on 24 March 2017.
She and Mr Satchwell met in Leicester, where Richard is from, when she was 19. They spent most of their married life living in Fermoy, Co Cork, where Ms Satchwell grew up.
They sold their home in Fermoy and moved to Youghal around 18 months before she disappeared.
Her mobile phone was left at home.
Mr Satchwell said she was devoted to her two dogs and her pet parrot. These were also left at the house.
Mr Satchwell described his wife as a generous person. She was one of a family of four sisters and three brothers.
Her family in Fermoy described her as fun and outgoing.
Her sister, Teresa Dingivan, said Ms Satchwell just would not get up and go.
"Tina would never walk away from family. No, never," Ms Dingivan said. "It is upsetting not knowing, wondering where she is, is she safe, does she have enough money. It does go through your head."
The garda investigation into Ms Satchwell's disappearance has remained active over the past six-and-a-half years.
Three months after she was reported missing, gardaí conducted a technical and forensic examination of the couple's three-storey home on Grattan Street in Youghal and of their car.
Two months later, gardai conducted forensic tests on two suitcases found by Mr Satchwell at a clothes bank in the carpark of a retail store in the town. He thought one of them may have belonged to his wife.
The tests did not establish any link between the suitcases and Ms Satchwell.
Later that month, the Garda Water Unit conducted a search of the shoreline in Youghal while members of the Garda Divisional Search Team searched an area of wasteland elsewhere in the town.
The most extensive search took place as the first anniversary of Ms Satchwell's disappearance approached in March 2018.
Gardaí cordoned off a 40-acre wood at Castlemartyr, between Midleton and Youghal.
The search of Mitchel's Wood continued for almost a fortnight before it was eventually wound down.
Again, it is understood, nothing of significance was found. The garda team kept working.
In March 2020, on the third anniversary of her disappearance, gardaí announced that they were conducting a peer review of the investigation to date into the disappearance.
At that stage, they confirmed that they had followed up more than 370 separate lines of inquiry, had viewed more than 100 hours of CCTV and had taken more than 170 statements.
Last March, on the sixth anniversary of her disappearance, gardaí renewed their appeal for the public's help.
"Any new information, no matter how insignificant it may seem, will be welcomed by the investigating team," they said.
