Dissident republicans in Belfast and Derry are being blamed for murders in both cities which the Police Service of Northern Ireland (PSNI) have described as brutal and cold-blooded.

A dissident paramilitary grouping calling itself the IRA has admitted shooting father-of-four Kevin Kearney, 46, in Belfast on Tuesday and dissidents are also believed to be responsible for the murder of Barry McCrory, 35, shot in Derry on Tuesday morning.

McCrory, who was shot dead by a lone gunman in Derry city center, was known to police for drugs activity.

PSNI Detective Chief Inspector Ian Harrison told the press the killing was a 'brutal execution' of an individual. 'No person has a right to be judge, jury and executioner,' he said.

Social Democratic Labour Party (SDLP) Assembly member Pat Ramsey was reportedly nearby when the shooting occurred. 'There is no doubt whatsoever that dissidents were involved. Once again there are those in our community who are intent on destroying the unity of purpose that can only benefit everyone, especially our young people,' he said.

Tourists who had visited the city as part of the UK City of Culture were in the city center area where the shooting happened he said, adding that he also saw the murdered man’s partner being taken away by ambulance 'in a terrible state of distress.'

'His father and mother and brother also came to the scene and could not be allowed see the body by the police. It was very emotional, very distressing,' he said.

The two killings happened in the same week which a major international investment conference to announce new jobs and opportunities for Northern Ireland occurs. The top tier event opened with a dinner in Hillsborough Castle yesterday followed by a conference in Belfast which the British prime minister David Cameron is scheduled to attend.

According to the Irish Times the dissident group that killed McCrory is suspected of being the same organization responsible for the murder of Kearney in Belfast. Kearney reportedly went missing when he brought his dogs for a walk on Tuesday after leaving one of his children to school. His body was later found in a lake in Alexandra Park in north Belfast.

Detective Chief Inspector Justyn Galloway told the press: 'Kevin was known to us for previous offending, but what I want to make clear is regardless of Kevin’s lifestyle, regardless of his previous offending, there is no justification whatsoever for someone to shoot him dead as they did.'

In a statement to the Irish News the dissident group announced that it killed Kearney 'in response to complaints within our community.'

But Sinn Fein Deputy First Minister Martin McGuinness said those responsible for the killings 'were not republican, they were not representative and they were entirely criminal in their motivation.'

The Northern Secretary Theresa Villiers has described the killings as 'abhorrent and brutal.'