The 9mm pistol and the letter found next to the lifeless body of Lt-Col Paul Alberto Ravone seemed to indicate suicide. Argentine human rights groups, however, suspect foul play - because he is not the first key witness in a baby-theft trial to turn up dead.
In a series of cases gripping the country, men and women are on trial for stealing newborn babies from political prisoners during the military dictatorship between 1976 and 1983. Couples faithful to the regime illegally adopted the babies, raising them free of "subversive doctrines". Meanwhile, their mothers were "disappeared", in many case thrown from planes into the sea, in what was known as the "Dirty War".
Ravone, 65 and retired, was due to testify next week in a case involving the theft of twins born in 1976.
Although police suspect suicide, the leader of the group searching for their grandchildren, Grandmothers of the Plaza de Mayo, expressed their doubts after Ravone's body was found on Monday. Estela de Carlotto says that witnesses are being "eliminated".
On 10 December, a key witness in a similar trial, Hector Febres, was found dead in his cell from cyanide poisoning. The Justice minister, Anibal Fernandez, says he has no doubt that Febres was murdered. The Dirty War is still being fought.
The discovery of Ravone's body follows two other incidents linked to the baby- theft trials. The first was a police raid on the home of Evelyn Vazquez, 30, seeking articles that might contain DNA after she refused to have a blood test. Nine years ago, her alleged biological grandparents launched an investigation to find out if Ms Vasquez was the child stolen from their daughter. She says she will do nothing to implicate the couple that raised her.
The second case could not be more different. Maria Eugenia Sampallo is pressing charges against the couple who raised her. She always doubted her identity and submitted herself to a DNA test in 2000. The results produced a grandmother and elder brother. Her parents, she found out, were arrested in October 1977 and never seen again.
Her adoptive parents, Cristina Gomez and Osvaldo Rivas, as well as a third accused, Enrique Berthier, suspected of giving the baby to Mrs Gomez, could spend 15 years in jail if convicted.
According to the Grandmothers organisation, at least 500 children were taken from their mothers. A DNA databank and constant campaigning by human rights groups have helped to resolve 88 cases.