The younger sister of Iranian student activist Akbar Mohammadi says her brother was tortured and then murdered at Iran’s Evin’s prison this past weekend.

In a phone interview yesterday from Turkey, Nasrin Mohammadi said she had received messages from her brother’s fellow inmates saying that he was poisoned by Evin prison guards.

Choking back tears, Ms. Mohammadi said, “I received two phone calls on Sunday from fellow inmates who told me, ‘Akbar was poisoned.'”

Already lawyers for the Mohammadi family have called for an independent investigation into the death of the student leader who was first arrested following the Tehran University uprisings of July 9, 1999.

Yesterday the BBC reported that the parents of Mohammadi were arrested at the Tehran Airport by the country’s intelligence ministry upon arriving in the country. A lawyer for the parents, Nemat Amadi, said yesterday that they were detained in order to quash public criticism.

The death of Mr. Mohammadi, who was engaged in a hunger strike at the time, is further evidence that Iran is stepping up its crack down on internal dissidents. This spring, the regime arrested a Canadian-Iranian philosopher and leading reformist, Ramin Jahanbegloo. In June, authorities arrested a former member of parliament, Ali Akbar Moussavi Khoeini. The death also comes as one of Iran’s leading oppositionists, Akbar Ganji, has said that the country’s liberal opposition would reject any financial assistance from America.

Ms. Mohammadi yesterday said that her brother was buried Monday and no one from the family was allowed to attend. She did however hear reports of the state of her brother’s body, which she said was pocked with bruises and marks of torture. “His mouth and eyes were still open,” she said. “The regime killed him. You have to tell people this.”

Mr. Mohammadi was a member of Joumbesh Jaryan Sevvom, also known as the movement of the third kind, a secular student movement in Iran distinct from the larger organization for student unity that has its roots in the Islamic revolution of 1979. An external spokesman for that organization yesterday also said that he had heard from fellow inmates of Mr. Mohammadi that he was poisoned.

Like almost all of the recent prosecutions and mistreatment of democracy activists in Iran, one suspect in Mr. Mohammadi’s death is Iranian prosecutor, Saeed Mortazavi, the same man who prosecuted Mr. Ganji and was responsible for sending Canadian-Iranian photographer, Zahra Kazemi to Evin prison in 2003, where she was murdered. Ms. Mohammadi yesterday said that Mr. Mortazavi had also spent time with her brother before his death. The regime sent Mr. Mortazavi to the opening plenary session of the new U.N. Human Rights Commission in June.

The death of Mr. Mohammadi has already drawn criticism from the White House.