The US Special Envoy to Northern Ireland, Mitchell Reiss, is meeting the sisters of murdered Belfast man Robert McCartney.
The McCartney sisters are seeking justice for their brother's killers
He was fatally stabbed outside a Belfast pub. His family have maintained IRA members were involved in the killing on 30 January.
Mr Reiss initially met the sisters in America in March when he assured them of the US administration's support.
The sisters' campaign has led to their nomination for a humanitarian award.
They have been shortlisted for the annual Robert Burns Humanitarian Award. Details of the winner are due to be announced in Ayrshire on Friday.
The women's brother - a 33-year-old father-of-two - was beaten and stabbed near Belfast city centre after a row in a bar.
He died later in hospital.
The sisters' quest for justice has taken them to the White House and the European Parliament, where they have won support from politicians and leaders.
Mr Reiss is to meet the sisters on Wednesday. Before the meeting he met Sinn Fein President Gerry Adams.
After the one hour meeting Mr Adams said he told the envoy that following the elections there was now an imperative to move the process forward.
Mr Adams said that while the DUP would have to be part of any revised institutions it did not have to give its permission for "other entitlements" including the equality agenda and a bill of rights.
After meeting Mr Reiss, the SDLP's Alex Attwood said the envoy agreed with them that there must be a very strong stand to end organised crime on the island of Ireland.
Mr Attwood also said Mr Reiss supported their view that whatever the DUP had planned, they were not going to do damage to the Good Friday Agreement.
On Tuesday, Mr Reiss had his first meeting with Northern Ireland Secretary Peter Hain in London.
Speaking afterwards, Mr Hain said America was a "powerful partner" in the efforts for peace in Northern Ireland.