THE cause of death of twin brothers -- who were found in an apartment by their mother -- will not be known for almost month.
However, it is understood that the deaths of Kevin and Peter Moran (29) in Limerick is drugs related.
Gardai are not treating the deaths as suspicious.
The brothers' bodies were found at a residence in the Harvey House complex near Limerick city centre on Wednesday afternoon by their mother, Margaret Moran.
Former defence minister and local TD Willie O'Dea described the deaths of the brothers as an "immense tragedy".
"From my work in the Old Cork Road area, I know of the family. It is an absolute appaling tragedy," he said.
Yesterday, state pathologist Marie Cassidy carried out post-mortem examinations on the brothers' remains at the Mid-Western Regional Hospital.
Following yesterday's examinations, Detective Inspector Tom O'Connor said the "outcome of both post-mortems were inconclusive, subject to toxicology analysis".
It is understood that toxicology testing from samples and blood taken could take at least three weeks.
The bodies of both men were returned to their family yesterday.
The brothers had been missing for up to a week and it is not yet known when they died.
A friend of the twins contacted their family on Wednesday, saying they had not been seen for several days.
The Irish Independent has learned that Ms Moran visited the apartment at Steamboat Quay on Wednesday afternoon but failed to gain admittance to the residence.
She then asked a member of staff at the apartment block to open the door and she discovered her dead sons inside.
Drugs paraphernalia was also found in the apartment.
Ms Moran -- a mother of six who is aged in her 60s -- was said to be distraught yesterday as she attempted to come to terms with her loss.
Kevin and Peter Moran had never come to the attention of gardai before and their deaths have shocked the city.
"They were fierce nice young fellas -- absolutely lovely," said one person who knew them.
They are originally from Georgian Village, Old Cork Road, Limerick, but spent recent years in England trying to get work in the construction trade.
One of their brothers, Greg, lives in Dublin; while another, John, is based in England.
"This is a dreadful time for the family -- for any family to suffer something like this," Mr O'Dea added.