A man in his 20s has been arrested in connection with the murder of PSNI Constable Stephen Carroll.
There are now three people being held as part of the murder investigation.
Yesterday the PSNI were given a further five days to question a 37-year-old man and a 17-year old-youth about the killing in Craigavon.
The latest arrest comes as hundreds of mourners from all faiths attended the funeral of Constable Stephen Carroll.
Constable Carroll was shot dead when answering an emergency call at a Craigavon housing estate on Monday night.
Constable Carroll's remains were brought from his family home in Banbridge, Co Down, to midday requiem mass at St Therese's Catholic Church.
Shops in the centre of Banbridge closed their doors as a mark of respect as Constable Carroll's coffin was taken to the church.
Hundreds of people lined streets, closed to traffic, in silence as the funeral cortege passed.
When the hearse arrived at the church, flanked by a guard of honour of 18 officers, six colleagues of Constable Carroll shouldered his coffin and carried it slowly into the church behind a lone piper playing a lament.
In his homily, the chief celebrant, Canon Liam Stevenson, said an attack on the PSNI was an attack on the people of Northern Ireland.
At the end of the service, PSNI Chief Constable Sir Hugh Orde paid tribute to Constable Carroll.
He said he was one of the ordinary men and women who did an extraordinary job, displaying a willingness, bravery and commitment to serve the community.
In a pledge to the officer's widow, he said: 'He will not be forgotten, Kate, I promise you. My staff and officers will not forget what he did, I know the community will not forget what he did.'
He said messages had come in from the global police family and they too would not forget.
The Chief Constable's unexpected contribution to the service was met with loud applause throughout the packed church.
The 48-year-old is survived by his wife Kate, a son and grandchildren.
He planned to retire from the PSNI in two years' time and start a career as a personal trainer.
The Government was represented by Minister for Justice Dermot Ahern and Garda Commissioner Fachtna Murphy was also present at the funeral mass.
Constable Carroll was the first police officer to be murdered in Northern Ireland since 1997.
The police were last night given a further five days to question two men about the murder.
The PSNI was established under the Patten Reforms of 2001 with new recruitment and accountability structures.
Sinn Féin sent policing spokesman Alex Maskey and local Assembly member John O'Dowd to the funeral.
Mr O'Dowd said it was time to give leadership to the community.
Northern Ireland Secretary Shaun Woodward and Security Minister Paul Goggins were also at the funeral.
Fine Gael leader Enda Kenny was represented at the funeral by the party's justice spokesman Charlie Flanagan.
President Mary McAleese has a series of engagements in Northern Ireland but she paused at 1pm for a minute's silence.
Watch an interview with Kate Carroll, Constable Carroll's widow.
