Caspian Makan, the fiancé of Neda Agha Soltan, a young woman killed in the recent protests in Iran, has been held in detention since 26 June, after he made a statement linking her murder to the pro-government Basij militia.

Currently held in Evin Prison in Tehran, Caspian Makan is reported to have told his family that if he signs a "confession" saying that the People's Mojahedeen Organization of Iran (PMOI), a political body banned in Iran since 1981, killed her, then he may be released.

Amnesty International said it fears he may be forced to sign such a "confession" under torture or other ill-treatment, given the pattern of human rights violations in Iran following the election. The organization said that he may be a prisoner of conscience, held for peacefully exercising his right to freedom of expression.

Neda Agha Soltan, 27, was killed on 20 June in Tehran. She was shot as she and three companions, including Caspian Makan, were leaving one of many demonstrations that took place following Iran's disputed presidential election on 12 June. While other demonstrators were trying to help her, a man with a mobile phone camera filmed her dying moments. The video footage was widely circulated on the internet and became a symbol of the unrest that developed in Iran.

In an interview with BBC Persian TV on 22 June, Caspian Makan said that "Eyewitnesses and video footage […] clearly show that probably Basij paramilitaries […] deliberately targeted her". It later emerged that a member of the Basij militia, a state security body under the command of the Revolutionary Guard, incriminated himself by exclaiming after her shooting that he did not mean to kill her. Caspian Makan was arrested at his home in Tehran four days later.

President Mahmoud Ahmadinejad is reported to have described Neda Agha Soltan's death as "suspicious". On 29 June he wrote to the Head of the Judiciary requesting that an investigation be undertaken into it.

However, in the days following her killing, a number of government officials made statements denying that the state security forces were involved in her death and, in some cases, blamed others.

Ayatollah Ahmad Khatami, a representative of the Supreme Leader, stated in Friday prayers at Tehran University on 26 June that the evidence showed that the protesters themselves killed her and did so as a way of making "propaganda" against the system.

The authorities have since intimidated Iranians who have spoken out about the killing. Chief of Police, Brigadier General Ahmadi-Moghaddam, is reported to have told a press conference on 30 June that the Iranian police and Ministry of Intelligence had issued an international arrest warrant via Interpol for the arrest of Dr Arash Hejazi, a doctor who tried to save Neda Agha Soltan's life at the scene and who spoke publicly about what he witnessed to international news media. The warrant accused Dr Arash Hejazi of spreading misinformation about the killing and thereby "poisoning the international atmosphere" against the Iranian government. Dr Arash Hejazi, as well as the TV journalist who interviewed Caspian Makan, have both left Iran, fearing for their safety.

The Iranian authorities are reported to have harassed and intimidated Neda Agha Soltan's family and other mourners after her death. Before burying her in Behesht-e Zahra Cemetery, in a section apparently set aside by the authorities for those killed in the unrest, her family were said to have been told by the authorities to ensure that no mourners other than family members attend the burial. They were threatened with unspecified punishment if they did not comply.

The authorities were also reported to have issued a ban on collective prayers for Neda Agha Soltan in mosques. When Agha Soltan’s family and other mourners tried to hold a commemoration service for her at Niloufar mosque in Abbas Abad, they were interrupted after 10 minutes by about 20 Basij paramilitaries, who entered the mosque and dispersed the attendees.

Amnesty International has called on the Iranian authorities to take immediate steps to protect Caspian Makan from torture or other ill-treatment while in detention and, in particular, to ensure that he is not forced to sign any "confessions" under such treatment.

The organization has urged that Caspian Makan be given immediate access to his lawyer, family and any medical treatment he may need. It has also called for his immediate and unconditional release unless he is to be charged with a recognizable criminal offence.