Sinn Féin leader Gerry Adams has insisted he was not involved in the murder of Jean McConville, following his release from police custody this evening.

A file is to be sent to the Public Prosecution Service.

Loyalist protesters attempted to block his exit from the station, but Mr Adams left by a back gate. 

The Sinn Féin President and Louth TD was questioned for four days by police in Co Antrim investigating the IRA abduction and murder of Ms McConville in 1972.

Speaking at a press conference following his release, Mr Adams said he was innocent of any involvement in the murder of Mrs McConville.

Mr Adams said he made himself available to talk to police following a "sustained, malicious, untruthful and sinister campaign" against him alleging his involvement in Ms McConville’s death.

While he said he was "concerned about the timing" of the arrest, he insisted that he fully supported the PSNI.

Mr Adams said he was "innocent of any involvement in any conspiracy to abduct, kill or bury Mrs McConville.

He added: "When the PSNI contacted my solicitor on Monday afternoon I was concerned about the timing, given that Sinn Fein is involved in a very important European election and local government elections across the island of Ireland."

In a statement this evening Northern Ireland Director of Public Prosecutions Barra McGroy said he will not take a decision on the files in relation to Gerry Adams, but this decision will be passed to his deputy.

This development was expected in light of the fact that Mr McRory has acted as solicitor to Mr Adams in the past.

Downing Street confirmed that David Cameron and Taoiseach Enda Kenny had spoken earlier in the day to discuss the situation surrounding Mr Adams' arrest, but would not give any further details of the call.

Meanwhile, Michael McConville, a son of Jean McConville called for an independent investigation by a team from outside Northern Ireland so no political pressure is applied.

Mr McConville described as an 11-year-old boy watching his mother be dragged in fear from her home in Divis flats in west Belfast by neighbours whom he recognised.

But he said he was too afraid to give their names in case he or his family are shot.

He said tonight: "We would like to see all the investigations taken out of Northern Ireland, we would like an independent body to do this so there is no political pressure on the police."

Mr McConville also vowed that his family's fight for justice would go on and said recent days had been difficult and stressful.

"The McConville family is going to stay to the bitter end of this till we get justice for our mother.

Earlier, Northern Ireland's Deputy First Minister Martin McGuiness reiterated his belief that the arrest of Mr Adams was politically motivated.

However, Northern Ireland's Justice Minister and Alliance Party leader David Ford rejected Mr McGuinness' claims of political policing.

DUP leader and Northern Ireland First Minister Peter Robinson earlier accused Sinn Féin of attempting "bullyboy tactics" over the PSNI in relation to the detention of Mr Adams.

Mrs McConville was dragged away from her children in the Divis flats in west Belfast by a gang of up to 12 men and women after being accused of informing to the security forces.

She was interrogated, shot in the back of the head and then secretly buried - becoming one of the "Disappeared" victims of the Troubles.

Her body was found on a beach in Co Louth years later, in 2003, 80km from her home.