Sources say that even seasoned detectives were left “horrified and shocked” by the extreme level of violence used in the attacks which occurred in the Eustace Street and Curved Street areas of Temple Bar at around 3.30am on the date in question.
A senior source explained: “We believe that what happened on the night was motivated by racism — that is racism against white people.
“When the suspects were first questioned they tried to use racism as a defence — they tried to say that they had been racially abused by the victims for being black.
“But absolutely no evidence of that was ever uncovered and gardai are satisfied that the culprits were not racially abused.”
The mother of one of the suspects has a conviction and served jail time for trafficking children into France from Nigeria.