text: Kevin McGuigan Sr was shot dead at his home at Comber Court in the Short Strand on Wednesday.
  Police believe two men shot him several times in the head and chest at point blank range before running off.
  The BBC understands the 53-year-old was one of a number of suspects in the murder of Gerard 'Jock' Davison in May.
  Sinn Féin has denied speculation that Provisional IRA may have been involved in his murder. The DUP said there will be "repercussions" if that is the case.
  Mr McGuigan, a father-of-nine, was taken to the Royal Victoria Hospital but died a short time later.
  BBC Northern Ireland home affairs correspondent Vincent Kearney said Mr McGuigan was killed by two masked men using semi-automatic weapons in a "professional, execution-style killing".
  Appealing for information, the officer leading the murder investigation said the gunmen were on foot and wearing dark clothing with their faces covered.
  "We need to hear from anyone who has information about the events of last night, about the movements of the gunmen both leading up to and immediately after the shooting," said Det Ch Insp John McVea.
  Mr McGuigan had been questioned by police after the murder of Jock Davison in the Markets area of Belfast three months ago.
  Mr Davison, 47, was a former IRA commander and a former friend of Mr McGuigan.
  The IRA pair were also founding members of the paramilitary group Direct Action Against Drugs (DAAD), which killed more than a dozen alleged drug dealers.
  They were later involved in a feud, and Mr McGuigan was shot several times in a so-called punishment attack.
  It was claimed that Mr Davison gave the order for that attack on his former friend.
  Det Ch Insp McVea said police were "aware of speculation around a possible motive" for the murder of Mr McGuigan.
  The detective said that in the investigation into the murder of Mr Davison, Mr McGuigan was questioned "as a potential witness, not a suspect", and this was still the police's position.
  "Speculation is not helpful and is potentially dangerous," he said.
  "People should allow the police investigation to take its course and provide any information they have to detectives."
  However, the police officer did not go as far as entirely ruling him out as a suspect.
  "I am saying the investigation team into the murder of Jock Davison would remain open minded as to who is responsible," he told a news conference.
  The detective also appealed for "those with influence in the community to use all their efforts to reduce tension and appeal for calm and restraint at this very difficult time".
  The victim's elderly mother, Margaret McGuigan, told the BBC that her son's killers would have to live with what they had done.
  She added there had been "too many murders" in the area and that she hoped her son's would be the last.
target: A former Provisional IRA member murdered in front of his wife was shot dead in a "ruthless and premeditated killing", police have said.