When gardaí asked murder accused Patrick Quirke why he had searched the internet for "body decomposition timeline" he told them his son had died and added: "That's all I'm saying."
Gardaí also put it to Mr Quirke that he had carried out similar internet searches before his son's tragic death in August 2012 but he denied that this "blew out of the water" his explanation.
Farmer Patrick Quirke, 50, of Breanshamore, Co Tipperary has pleaded not guilty to the murder of Bobby Ryan, a part-time DJ known as Mr Moonlight.
Mr Ryan went missing on June 3, 2011, after leaving his girlfriend Mary Lowry's home at about 6.30am.
His body was found in an underground run-off tank on the farm owned by Ms Lowry and leased by the accused at Fawnagown, Tipperary 22 months later in April 2013. The prosecution has claimed Mr Quirke murdered Mr Ryan so he could rekindle an affair with Ms Lowry, 52.
Detective Inspector Seamus Maher told prosecution counsel Michael Bowman SC that gardaí arrested Mr Quirke on suspicion of Mr Ryan's murder on June 19, 2014, and interviewed him the following day at Tipperary Garda Station.
During those interviews, Det Insp Maher agreed with counsel that gardaí asked Mr Quirke about a computer hard-drive labelled as KKPQ1 which was seized from Mr Quirke's home in May 2013 and which gardaí said they had identified as belonging to the accused.
A computer expert, they told him, had identified searches relating to the limitations of DNA evidence carried out some time before September 2012 and other searches relating to human decomposition on December 3, 2012.
Gardaí asked him if he could eliminate his wife and children as the people who carried out those searches.
He responded that he didn't know what they meant. He also said he was not familiar with "in private browsing" when gardaí asked if he activated a private browsing session when carrying out the searches.
They asked if there was any explanation for those searches and he replied: "My son had recently died. That's all I'm saying."
Gardaí put it to him that he was searching for decomposition because he knew where Bobby Ryan's body was and was trying to establish what condition it would be in.
He said that if he knew where Bobby Ryan was all he would have to do is open the lid of the tank and look in.
He said it wouldn't make sense for him to search for decomposition on the internet when he had full access to the tank at all times.
He further described as a "load of crap" the theory that he alerted gardaí to the body because he wanted to be "in control" and didn't want it to be found by someone else. He asked them why he would bring this "nightmare" on himself.
Gardaí later returned to the internet searches and confirmed that Mr Quirke's son Alan died on August 4, 2012.
Gardaí said they had reviewed the evidence and found a search for "body decomposition" on July 25, 2012.
They said this "blows out of the water" his explanation.
Mr Quirke said his explanation wouldn't account for every search. He said the previous search does not "blow out of the water" his explanation for the searches on December 3, 2012.
The trial continues in front of Justice Eileen Creedon and a jury of six men and six women.