The Chief Constable has defended a high profile PSNI operation into the murder of Ronan Kerr in a public clash with Martin McGuinness over police tactics.
Matt Baggott said the investigation will not be politically influenced after the Deputy First Minister (below) criticised a series of raids and arrests earlier this week by officers investigating the Catholic PSNI constable's murder and related dissident republican activity.
Five men were arrested after 200 police officers raided seven properties across three counties on Tuesday morning. All have since been released without charge.
A 23-year-old woman arrested in Omagh on Wednesday in relation to the murder was released yesterday.
Mr McGuinness said while he supported the police in their attempts to find those responsible for the murder, the operation would not help bring his killers to justice, and criticised the arrest of a 22-year-old man.
He said there was no way the individual in question could have been involved in Mr Kerr's murder, and the arrest cast doubt on the quality of the investigation.
Hitting back at the comments, Mr Baggott said that criticism of the investigation was "premature". He said the probe was "complex and will take considerable time to complete".
"It is being conducted under the law and future charges remain the responsibility of the independent Public Prosecution Service," he said. "My assurance is that the investigation will remain methodical and relentless and will continue to be absolutely impartial and completely free of political influence.
"I am very satisfied with the professionalism and progress to date and will be reporting on this to the Policing Board in due course. The Policing Board is the appropriate place for scrutiny to take place, particularly during a live and sensitive investigation."
The 22-year-old man, whose arrest in Coalisland provoked the Deputy First Minister into publicly criticising the police operation, is now launching legal proceedings against the Chief Constable for wrongful arrest, his solicitor Padraig Ã“ Muirigh said.
Mr Ã“ Muirigh said the man's arrest "appears to have been made on dubious intelligence and without any evidential basis".
He added: "No evidence was produced during the course of my client's detention that linked him to any unlawful activity. He was released after evidence showed he was in the United States at the time of Constable Kerr's death.
"It appears little thought has been given to the propriety or legality of the methods used by the PSNI in the arrest of my client, the search of the family home, and to the damage to confidence in policing in the Coalisland area as a result of the actions of the PSNI."
The 22-year-old was one of five men arrested during a series of raids in Coalisland, Toomebridge, Bellaghy and Ballyronan.
PSNI constable Ronan Kerr was killed by a dissident republican car bomb outside his home in Omagh on April 2.
The 25 year-old Catholic, who joined the police in May 2010, was the second officer to have been killed since the RUC became the PSNI in 2001. A number of people have been questioned in connection with his murder.