The IRA man murdered in the Short Strand on Wednesday night was reportedly a suspect in the killing of Jock Davison earlier in the year.
Mr Davison had been shot on the morning of May 5 in the Markets neighbourhood.
Both the Short Strand and Markets are strongly republican residential areas, and stand to the east and south of Belfast city centre respectively.
Multiple media sources claimed that Wednesday’s victim Kevin McGuigan had been a suspect in that earlier shooting.
A police spokesman would not confirm the claim. on Thursday morning.
Late last night, First Minister Peter Robinson MLA issued a statement which said: “Terrorism was always wrong and must be condemned.
“I know that the vast majority of people in Northern Ireland do not want to see this kind of activity back on our streets.
“I would hope that those responsible can be quickly identified and brought to justice.”