Elements on the far right used the killing of Ashling Murphy to whip up racist and anti-immigrant sentiment, according to a civil rights organisation.
The Irish Council for Civil Liberties said that the online commentary in relation to the killing in Tullamore on January 12 highlights the responsibilities of social media companies to address “the spread of misinformation”.
In a statement, the executive director of the ICCL Liam Herrick said: “The exoneration of an innocent man from suspicion of involvement of Ashling Murphy's murder is an important reminder for us all.
He continued: “It's very troubling that some far-right actors used Ashling's murder to whip up racist, anti-immigrant sentiment."
A Romanian man who was arrested following the killing of Ashling Murphy was released without charge and gardaí said he had been eliminated from their enquiries.
He was cleared as a suspect in the case after the results of forensic tests came back, comparing his DNA and fingerprints to those found at the scene, which ruled him out.
Two men have since been arrested in connection with the investigation, with one being held on suspicion of withholding information.
After the innocent Romanian man's arrest, online platforms were used to raise concerns about immigration, with one post declaring that Ireland’s borders are open to “the world’s trash”.
Another post slammed “foreign scum” while others criticised “Irish liberals” for being critical of racist commentary online. There has also been criticism of Ireland for being “way behind the curve on what’s been happening across Europe”.
A Garda statement issued on Monday evening urged people against commentary online.
“An Garda Síochána is aware and continues to be concerned about the activity of persons who are sharing information on social media, and in particular private messaging apps," the statement read.
"If you have information which is relevant to this criminal investigation, you should contact the investigation team at Tullamore Garda Station with this information.”
Sources said that there is concern about material being spread online, and in private messaging apps, regarding the identities of persons of interest in high-profile investigations because of fear that extremists could target them, their relatives, or their property.