Saverio Bellante has been found not guilty of murder by reason of insanity.
Mr Bellante (36) had admitted killing Tom O'Gorman in Castleknock in Dublin last year, but denied his murder.
He kept his head bowed as the jury foreman told the court that they had come to a decision, after one hour and 36 minutes of deliberation.
By unanimous verdict, the seven men and five women found the Sicilian man not guilty by reason of insanity.
In her direction to the jury before lunch, Judge Margaret Heneghan had told the jury that the law requires them to find Mr Bellante not guilty by reason of insanity if he fulfils the criteria under the law, which he did.
Two psychiatrists testified that Mr Bellante was operating under a psychotic episode when he killed his landlord in January 2014 with a knife and a dumbbell.
Mr Bellante was committed to the Central Mental Hospital, where he has been since the offence.
He is to return to court again on August 12th.
Judge Heneghan also ordered that Mr Bellante be assessed by an appropriate medical officer.