On Wednesday, Mr Paisley said police officers involved in the killing of Colum Marks should be given medals rather than face investigation.
Marks, 29, was shot in 1991 in Downpatrick, County Down.
Sinn FÃ©in's Mickey Brady said Mr Paisley's comments were "crass and disgusting".
"No one can be above or beyond the law, whether he is a friend of Ian Paisley's or not," said the Newry and Armagh MP.
"This is a further indication of the DUP's attempts to whitewash the past and it is symptomatic of their abject failure to deal with the legacy of the conflict."
A new investigation was to be launched into Marks' killing in June 2016 after a new eyewitness account emerged.
Mr Paisley said the man who fired the shot would be "traumatised" by another investigation.
He added the British government should be honouring the Royal Ulster Constabulary (RUC) officer and his team for "taking out one of Ulster's worst terrorist criminals" rather than "dragging them through the process of constantly going over what they did".
The police officer who fired the shots previously said he believed Marks was armed at the time, and claimed he refused to stop when an attempt was made to arrest him.
No gun was ever found, and his family claimed Mr Marks was shot after being arrested.
Sinn FÃ©in has described the DUP's Ian Paisley's comments over the fatal shooting of an IRA man 26 years ago as "disgraceful".