— Gerry Adams, the president of Sinn Fein, will not be prosecuted in connection with the abduction and murder in Northern Ireland of Jean McConville, a Belfast woman who was tortured, shot and secretly buried by the Irish Republican Army in 1972, the authorities said on Tuesday.
Northern Ireland’s public prosecution service said it would not bring charges against Mr. Adams, or six others who had been questioned by the police, because there was little hope of securing a conviction in the case, which continues to haunt Sinn Fein after 43 years.
Sinn Fein was once the political wing of the Irish Republican Army, which suspected that Mrs. McConville, a 37-year-old widowed mother of 10, was a British informer. She was torn from the arms of her young children in her home in the Divis Flats housing complex of West Belfast
by about 12 men and women.
Mr. Adams, who has always denied any involvement in the I.R.A. or in Mrs. McConville’s killing, was detained and questioned over the murder for four days in April 2014. After his release, he said in a statement that a “sustained, malicious, untruthful campaign” was being waged against him.
For decades, the I.R.A. rejected reports that Mrs. McConville was among the so-called disappeared — suspected informers who had been dumped in unmarked graves. Her remains were found on a beach south of the border, in Ireland, in 2003 after a storm uncovered them.
Pamela Atchison, the deputy director of public prosecutions, said in Belfast that the evidence against the seven individuals, including Bobby Storey, a leader of Sinn Fein, came from a number of disparate sources.
Two senior I.R.A. activists told researchers working on a historical project sponsored by Boston College that Mr. Adams had given the order for Mrs. McConville’s abduction and murder. The two activists have since died.
An eighth suspect, Ivor Bell, 78, a leader of the I.R.A. in the 1970s, still faces charges of soliciting the killing. The decision to prosecute Mr. Bell is based on testimony that the authorities believe that he provided as part of the research project, although he has denied any involvement.
The research — by a veteran Northern Ireland journalist, Ed Moloney, and a former I.R.A. prisoner, Anthony McIntyre — involved the compilation of oral testimony from paramilitary fighters.
The researchers had promised the participants that their testimony would remain sealed until after their deaths, but a United States court ruled in 2013 that the police in Northern Ireland should be allowed to listen to the tapes.
Michael McConville, one of Mrs. McConville’s sons, said after the announcement on Tuesday that his family’s campaign for justice would continue.
“Those who ordered, planned and carried out this war crime thought that their guilt could disappear along with her body,” he said. “But it has not, and we will continue to seek justice for our mother and see those responsible held to account, no matter how long it takes.”