The Guatemalan government has accepted responsibility for the murder more than 12 years ago of Guatemalan academic Myrna Mack Chang.
Dr Mack, who gained masters degrees from the universities of Durham and Manchester, was stabbed to death outside her office in Guatemala City in 1990.
Her family says the killing was ordered by the Presidential Security Staff, which is responsible for the security of the president and vice-president and their families.
Newspaper Prensa Libre reported that foreign minister Edgar Gutierrez had announced the state's acceptance of responsibility in a letter to the Inter-American Court of Human Rights.
Former high-ranking officers in the Presidential Security Staff are in custody, accused of planning and ordering the murder.
Dr Mack's killer, Noel de Jesus Beteta, was sentenced to 35 years in prison in 1993, 25 years of which were for the murder.
Helen Mack, the dead woman's sister, said her sister was killed because of her work. Dr Mack was collecting information on people displaced because of the Guatemalan civil war. She planned to write a book based on the accounts of the displaced peoples. Many close to the case say the book would have exposed the Guatemalan army's brutally repressive activities.
A three-day trial at the Inter-American Court of Human Rights in San Jose, Costa Rica, last month began with a similar admission by the Guatemalan government, dismissed by Dr Mack's lawyers as "insufficient".
That trial ended acrimoniously as the Guatemalan government failed to admit full responsibility. At one point, government representatives walked out of the hearing. In his letter to the court, Mr Gutierrez apologised for this.
The domestic trial of the alleged masterminds behind the murder has been adjourned.