Tallaght Regional Hospital has begun a review of patient cases after it emerged that the nurse at the centre of the Garda inquiry at Naas hospital also worked there.
The inquiry, which centres around allegations that up to three patients were given drugs they had not been prescribed, has already led to the exhumation of the body of a 77-year-old man in Baltinglass, Co Wicklow, on Friday.
A spokeswoman for Tallaght Hospital, one of the largest in the State, confirmed to The Irish Times that the nurse at the centre of the Naas allegations had worked at Tallaght.
Up to 500 case notes will have to be reviewed in Tallaght and other facilities where the nurse worked in the last nine months as part of a wider investigation into her career history.
The 31-year-old woman from the west of Ireland worked as an agency nurse with the respected firm Nurse on Call. She worked in Tallaght between November 2002 and January 2003, and for two other medical facilities during the same period. She had been working at Naas General Hospital from January until early July, when she was suspended following complaints by colleagues.
These centred around allegations that she had administered a powerful tranquilliser, haloperidol, to a patient to whom it had not been prescribed. The nurse has denied the allegations.
"We're conducting an incident review, and that is under way at the moment," a spokeswoman for Tallaght said.
The hospital's authorities became aware only at the weekend that the nurse at the centre of the Naas inquiry had also worked there. The Tallaght inquiry is the latest to have been sparked by the allegations at Naas.
Apart from the Garda investigation, a separate independent inquiry by the South Western Area Health Board, which runs Naas Hospital, is also under way.
An Bord Altranais, the regulatory body for nursing, is expected to meet this week to discuss the matter. It has the power to instigate a fitness to practise investigation against any nurse registered in the state, and can seek a High Court order removing a nurse from its register temporarily.
In a statement on Sunday, Nurse on Call confirmed the nurse at the centre of the inquiry had worked for "three other hospitals/clients" apart from Naas. "Since 21st January she had worked solely at Naas General Hospital," the statement said. "Prior to the recent allegations we did not receive any complaints regarding this nurse."
Gardaí are now awaiting the results of toxicology tests from Friday's exhumation.
On Friday morning last, gardaí from Naas exhumed the body of 77-year-old Mr John Gethings, who died at the hospital on March 1st. He had spent a week in the hospital for treatment of a heart condition.