The SDLP has called on a member of Sinn Féin, who was in a Belfast bar on the night Robert McCartney was murdered, to go to the police and the police ombudsman's investigators.
Mr McCartney died after being stabbed and beaten outside the bar on 30 January.
The Sinn Féin Assembly election candidate, Cora Groogan, has confirmed she was among around 70 people in the bar when the row began.
Ms Groogan, who ran for Sinn Féin in the November 2003 Assembly elections in the Mid Ulster constituency, has said she saw nothing inside the bar and confirmed she had given a full statement to her solicitor.
The SDLP's Deputy Leader, Alasdair McDonnell, said it was useless for Ms Groogan to give a statement to a solicitor and that she should go to the police and the police ombudsman's investigators.