More than 60 gardaí, detectives and technical experts are continuing their investigation today into the double murder of Michael and Denis Hanrahan in Co Kerry earlier this week.
The father and son were found dead in their nightclothes at their bungalow near the village of Moyvane on Thursday morning.
Both men had been shot a number of times, but gardaí say a motive for the crime is still unclear.
The two victims were found dead in the same bedroom, where up to eight spent shotgun cartridges were discovered.
Reports this morning say gardaí believe they knew their killer, as there was no sign of forced entry.
A shotgun that may have been used in the murders has also been found in the house and has been sent for ballistic and forensic tests.