A black man went to the gallows alone today after a judge granted a stay of execution to the ``Sharpeville Six,'' who were aided in their appeal by an international clemency campaign. The pre-dawn hanging of Tsepo Letsoara, 24, concluded without fanfare, while world leaders, clergymen and politicians continued to plea with the government to save the ``Sharpeville Six.'' Letsoara was convicted of the murder of a black woman in a Port Elizabeth township in October 1985, during nationwide racial unrest. The victim, Grace Mvetye, was killed by the ``necklace'' method, in which a gasoline-soaked tire was placed around her neck and set ablaze. The ``Sharpeville Six,'' five black men and a woman, would have joined Letsoara on the gallows today had Pretoria Supreme Court Justice Willem Human not granted a one-month stay of execution Thursday. Human made his decision after defense lawyers presented evidence of perjury by one of the prosecution's chief witnesses. Human granted the convicts four weeks to apply for a retrial. The case was controversial because the six were convicted under the principle of ``common cause,'' which held them responsible for the September 1984 death of town councilor Jacob Dlamini because they among a mob of 100 that stoned and burned Dlamini to death in Sharpeville. Dlamini was killed on the first day of riots that lasted nearly three years and claimed more than 2,500 black lives. President P.W. Botha had ignored pleas from leaders of most Western nations and from countries and organizations around the world to stop the executions. The government said Human's decision ``proves the wisdom of the state president and his ministers in deciding not to impede the due process of law. The government also indicated a link between the scheduled hangings and a car bomb that exploded Thursday in Krugersdorp, killing three black people and injuring 20 people. The explosion occurred in a Magistrate's Court where the Sharpeville Six had been held briefly between their arrest and trial. Police offered a $25,000 reward for information leading to the arrest of a white man they say is a member of the outlawed African National Congress. The man was described as the prime suspect in the bombing. Deputy Minister of Information Stoffel Van der Merwe said neither pressure from overseas nor car bombs would persuade the government to interfere in a court case. The Star, an independent Johannesburg newspaper, reported today that Botha granted clemency three weeks ago to a black policeman who was sentenced to death for murdering a youth two years ago in Mamelodi, the black township outside Pretoria. A spokesman for the Department of Justice said Botha commuted Constable George John Sindane's death sentence to eight years in prison. The spokesman said Sindane was one of five people whose death sentences were commuted this year. In other developments Thursday, _ Attorneys said a $2.25 million wrongful arrest lawsuit was begun against the Ministry of Law and Order after charges of sedition and subversion were dropped against a black Roman Catholic nun and 13 others who lived in black townships outside Krugersdorp. Sister Bernard Ncube, president of the Federation of Transvaal Women, spent 16 months in detention, including 13 in solitary confinement, after being charged. The state alleged that the group established ``kangaroo'' courts, campaigned against the police and initiated a boycott of white-owned shops and buses. The charges were dropped Thursday after the prosecution refused to supply a court with details of the alleged acts. _Also, the attorney for freed African National Congress leader Govan Mbeki said the government denied his request for a passport, which he sought to visit his three children living in exile. Attorney Priscilla Jana said no reason was given for the denial. Mbeki was freed from prison in November after serving 24 years of a life sentence for treason and sabotage in connection with his activities as national chairman of the ANC. His oldest son, Thabo, is an executive member of the ANC in exile in Lusaka, Zambia. Since his release from prison, Mbeki has been restricted to the Port Elizabeth area, and banned from giving public speeches or news interviews.