The sisters of murdered Belfast man Robert McCartney have asked the US government and political leadership to maintain pressure on Sinn Féin to help bring his killers to justice.
During their second visit to Washington, Catherine and Paula met US special envoy for Northern Ireland Mitchell Reiss, State Department officials and politicians from both political parties, including senators Edward Kennedy, Hillary Clinton, Chris Dodd and Patrick Leahy.
Catherine McCartney said the family was grateful for the support the family's campaign has received in the US.
"We're pleased to report that their keenness, interest and sincerity is still there," she said.
Ms McCartney said the family believes Sinn Féin could do "a lot more" to help the investigation into her brother's death if the party encouraged witnesses to co-operate with the Police Service of Northern Ireland (PSNI).
"It's lack of co-operation with the police investigation which is preventing the murderers from being brought before the courts," she said.
Mr Reiss said Mr McCartney's murder was one of many tragedies which have been happening in the North and would continue to happen until Sinn Féin endorsed the police force.
"Our view is that this tragedy can only have some meaning if the perpetrators are brought to justice and Sinn Féin endorses policing," he said.
Sinn Féin president Gerry Adams cancelled a visit to the US last week after the administration denied him permission to raise funds in the country because of the party's policy on policing.
Ms McCartney said she and her sister paid the entire cost of this week's visit to Washington themselves.
