Mr Barr was shot a number of times in an inner city pub last month
A man has been arrested in connection with a gangland murder in Dublin last month.
The man in his mid-30s is being held at Bridewell garda station over the murder of Michael Barr.
Mr Barr (35) was shot a number of times in the Sunset House in Summerhill on April 25th.
Meanwhile, gardaí are continuing to question three people in relation to the murder of Gareth Hutch on North Cumberland Street on Tuesday morning.
Two of those people were arrested yesterday evening.