Mr Nkencho died outside his Dublin home in December after being shot multiple times by members of the Garda while allegedly brandishing a knife.
A candlelit walk has taken place to mark the first anniversary of the death of George Nkencho.
He was suffering from mental health issues at the time.
Mr Nkencho’s death is the subject of an investigation by the Garda Siochana Ombudsman Commission (GSOC) which is not yet complete.
A walk took place in Blanchardstown village on Thursday evening finishing at the local Garda station where speeches were heard by his sister Gloria TD Brid Smith and former TD Ruth Coppinger.
In a statement on the first anniversary of his death, the Nkencho family described a “catastrophic year”.
“What happened to George should never have happened.
“Whatever George did, he should be alive today,” they said.
They also expressed disappointment that the GSOC investigation has not completed and called for a public inquiry into the killing.
“From the outset, our family has called for a public inquiry that would have the transparency, resources and power to get to the truth of what happened and why George was brutally shot dead within minutes on our doorstep, rather than the talking he so clearly needed,” he said.
“This is the first black person to be killed by the Gardai.
“How this is investigated and dealt with will set the tone for how Gardai deal with vulnerable people or minorities.
“If the Gardai responsible for the death of our son and brother aren’t held to account, it will have repercussions for how minorities view the Irish state and police.”