The PSNI are manipulating their investigation into the murder of Robert McCartney to cause political damage to Sinn Féin, Martin McGuinness claimed this afternoon.
Having earlier today strongly denied issuing a threat to the McCartney family, Mr McGuinness later challenged PSNI chief constable Hugh Orde to explain why people who could have important information about the murder have not been interviewed.
Mr McGuinness said: "Yesterday the PSNI turned away two key people in the McCartney murder investigation, a key witness and a key suspect.
"They have been raiding homes in Belfast looking for this man yet when he offers himself for interview they turn him away.
Mr McGuinness questioned why there has been no identity parade to date and claimed witness testimony identifying some of those involved in the attack has been ignored.
"Yesterday, in comments which were grossly misrepresented, I said that there are elements that are prepared to manipulate the McCartney case for political advantage. The PSNI is clearly involved in such manipulation.
"The PSNI's approach is not about justice; it is about damaging Sinn Féin," he said.
Earlier he rejected suggestions that he was threatening the McCartney sisters when he said they should be careful not to politicise their campaign to have their brother's killers brought to justice.
Speaking on television last night Mr McGuinness said: "The McCartneys need to be very careful. To step over that line into the world of party politics can do a huge disservice to their campaign."
The comments prompted another wave of negative publicity at a time when the party is under unprecedented pressure at home and abroad over its handling of the murder of Robert McCartney.
Mr McGuinness said his comments were intended to be "a word of friendly advice from someone who is 100 per cent behind their campaign for truth and justice.
"What I am flagging up here is the fact that on the streets some people are making comments to me - and I think it is a growing feeling - that the McCartneys shouldn't allow their campaign, which is for truth and justice, to be undermined by elements around them who are party political and who have got an agenda in relation to Sinn Féin," Mr McGuinness said.
SDLP policing spokesperson Alex Attwood said Mr McGuinness's comments were an example of Sinn Féin "double-think".
"For weeks, members of the IRA and Sinn Féin have refused and avoided helping the police with witness statements," Mr Attwood said.