The Irish Council for Civil Liberties (ICCL) has written to the Garda Síochána Ombudsman Commission (Gsoc) urging it to take eyewitness statements from members of George Nkencho’s family who were present at the time of his killing.
The ICCL said it was "concerned" that these statements had not already been taken and stressed that they were required under international law and to restore confidence in the Gsoc investigation.
Mr Nkencho, 27, was shot dead by the Garda Armed Support Unit outside his house on December 30 last.
There had been a disturbance in the housing estate in Clonee and Mr Nkencho was armed with a kitchen knife and attempts had been made to restrain him using pepper spray and deploying Tasers. His family said he been suffering from mental health issues in the preceding months.
News reports on Sunday suggest that a preliminary pathology report commissioned by the family's lawyer found Mr Nkencho was hit twice in the back.
The ICCL said there were obligations under international law to fully investigate the killing of George Nkencho by gardaí, including the need to fully investigate the possibility of racial bias, and to include and update Nkencho’s family at all stages of the investigation.
Doireann Ansbro, ICCL’s head of Legal and Policy, said: “We’ve called on GSOC to interview the Nkencho family as soon as possible in order to restore confidence that the investigation will be thorough.
"We’ve also called on them to take into account all of the gardaí’s human rights obligations including the prohibition on discrimination.
"We think there is a need to ensure they investigate potential bias — both explicit and implicit. In order to really examine this, it may be necessary for Gsoc to recommend a wider systemic inquiry following the current one. "
ICCL also published a briefing note on the State’s obligations when it uses lethal force and said part of Ireland’s human rights obligations is that the family of the victim be included at all stages of the process.
It said it was essential that any investigation be undertaken as promptly as possible in order to ensure the confidence of the community involved.
In this context, it is particularly worrying that the Nkencho family have yet to be interviewed by Gsoc, it said.
The ICCL said if the Gsoc investigation does not fulfil the requirements under Article 2 of the European Convention on Human Rights (on the right to life and right to an independent, effective, thorough and prompt investigation where there is lethal use of force by the State), "another form of inquiry will likely be necessary".