Mr Bellante, from Palermo, Italy, appeared at a Dublin court on Monday but offered no plea. He was without lawyers and told the judge he wanted to represent himself, adding that he would reject state-funded legal aid.
Detective Patrick Traynor testified in court today that, when charged with murder in police custody earlier, Mr Bellante replied: "I am guilty."
He will now be held without bail in Dublin's Cloverhill Prison, and Judge David McHugh ordered he receive a psychiatric evaluation ahead of his next court appearance on Friday.
Mr Bellante had worked in Dublin for the past two years at a pharmaceutical company, and rented a room from Mr O'Gorman after the Irishman's mother passed away in 2012.
Mr O'Gorman was a regular contributor to the Iona Institute, a conservative Catholic group which lobbies against same-sex marriage and abortion rights.
The scene in Castleknock, north Dublin where Tom O'Gorman was stabbed to death The scene in Castleknock, north Dublin where Tom O'Gorman was stabbed to death Iona Institute director David Quinn said Mr O'Gorman sometimes travelled to Italy to attend retreats run by the Focolare movement, a Catholic group which seeks to promote Christian unity.
He said O'Gorman loved the Irish rugby team, Liverpool football club and history, the subject he studied at bachelor's and master's level at University College Dublin.
"He had lots of opinions and liked a good argument, but he was good fun," Quinn wrote in a tribute published Monday.
- UK Independent