Detectives were granted extra time Friday evening to question Sinn Fein leader Gerry Adams in one of Northern Ireland’s most notorious killings.

Adams has strenuously denied involvement in the 1972 shooting of a mother of 10 whose skeletal remains were found on a beach in Ireland in 2003.

But in tape-recorded interviews handed over by Boston College, former members of the Irish Republican Army implicated Adams in the killing of Jean McConville.

Adams was arrested Wednesday evening under the Terrorism Act 2000, and police initially had 48 hours to question him. On Friday evening, a judge granted police another 48 hours.

Adams’s arrest has highlighted Northern Ireland’s struggle to deal with historical claims and injustices stemming from its bloody past while not upsetting the delicate peace project that’s followed the Good Friday Agreement signed in 1998.

Northern Ireland Minister of Justice David Ford speaks to the media outside Antrim police station in Northern Ireland on Friday. Police continue to question Sinn Fein leader Gerry Adams in the 1972 killing of Jean McConville. (Peter Morrison/AP)

Adams, 65, is a hugely significant political figure in the British Isles. He is a member of the Irish parliament and the longtime president of Sinn Fein, the former political arm of the IRA that’s now part of the power-sharing government in Northern Ireland.

His party, which is doing well in opinion polls, said the timing of Adams’s arrest was politically motivated and designed to cause electoral damage ahead of local and European elections this month.

Analysts said that regardless of whether Adams is ultimately released or charged, the police questioning is likely to further inflame tensions in still-polarized Northern Ireland.

“It’s very tricky politically,” said Eunan O’Halpin, a professor of contemporary Irish history at Trinity College Dublin. He said that neither the British nor the Irish government wants to see Sinn Fein damaged by these events because they are “in a sense holding it together on the Irish Republican side.”

But he noted that the pressure on authorities to act in the McConville case as evidence comes to light remains intense “because this is murder, and across the board, there are families seeking justice for a loved one’s death.”

The case of McConville, a widowed mother of 10 who was killed in 1972 — the bloodiest year of the Northern Ireland conflict — arouses particularly intense feelings. McConville, 37, was at her home in west Belfast when a group of men and women from the IRA burst in and dragged her from her screaming children. She was later shot in the back of the head. In 1999, years after her death, the IRA admitted that they had killed her because they wrongly believed she was an informant for the British army.

Her story came into sharp focus after Boston College was forced to hand over transcripts to the Police Service of Northern Ireland. As part of an oral-history effort known as the Belfast Project, researchers at Boston College, which has strong ties to Ireland, interviewed members of militia groups who fought on both sides in Northern Ireland’s conflict on the condition that their testimony would be released only posthumously.

But two years ago, following a request by British authorities, a U.S. District Court judge in Boston ruled that interviews relevant to the death of McConville be handed over. Since then, seven people have been arrested in connection with her killing, including Ivor Bell, 77, a former IRA leader who was charged last month with aiding and abetting her murder. He denies the charges.

McConville was the most famous of the “disappeared,” the name given to a group of 16 people who were killed and secretly buried by paramilitary fighters during the Troubles, as the 30-year period of violence that engulfed the nation is known.

In 1999, the British and Irish governments set up the Independent Commission for the Location of Victims’ Remains, whose aim is to gather information that could lead to recovery of the bodies. Nine bodies have been found.

Despite symbolic instances of reconciliation of late — such as Martin McGuinness, a former IRA commander who is deputy first minister of Northern Ireland, toasting the queen at Windsor Castle — there is still deep-rooted antagonism and suspicion in Northern Ireland.

“It’s still very raw,” said Diarmaid Ferriter, a professor of modern Irish history at University College Dublin. “There are still so many families who are carrying great pain and seeking justice.”

Following Adams’s arrest, some of McConville’s children have given powerful interviews, including her son Michael, who was 11 when his mother was taken. He said he knows who abducted his mother but remains too frightened to speak out.

“If I told the police now a thing, me or one of my family members or one of my children would get shot by these men. Everybody thinks this has all gone away; it hasn’t gone away,” he told the BBC.

But his sister Helen McKendry told the BBC that she was finally prepared to name names, saying: “I do not fear the IRA anymore. I will happily give the names that I know to the police.”