A viral video of a man appearing to display his decapitated young wife's head in the street after he discovered her alleged adultery has deeply shaken Iranians.
Police suspect that Mona Heidari, 17, was killed by her husband and brother-in-law in the southwestern city of Ahvaz, Iran's ISNA news agency reported.
By Monday, officers had arrested the two men "during a raid on their hideout", state news agency IRNA said, citing local police.
The case prompted Iran's vice president for women's affairs, Ensieh Khazali, to call on parliament to take "urgent measures" and on the authorities to raise awareness to prevent such cases.
Iranian newspapers and social media saw an outpouring of shock and rage over the killing, with many demanding social and legal reforms.
"A human being was decapitated, her head was displayed on the streets and the killer was proud," said the reformist daily Sazandegi.
"How can we accept such a tragedy? We must act so that femicide does not happen again."
Renowned feminist filmmaker Tahmineh Milani wrote on Instagram: "Mona was a victim of devastating ignorance. We are all responsible for this crime."
Following Heidari's murder, calls were revived to reform laws for the protection of women against domestic violence and to raise the legal age for marriage, currently set at 13 in Iran.
According to Iranian media, the victim was just 12 when she was married, and had a three-year-old son by the time she was killed.
Lawyer Ali Mojtahedzadeh, in the reformist paper Shargh, blamed "legal loopholes" for "paving the way for honour killings".
Fellow member of parliament Elham Nadaf told the ILNA news agency: "Unfortunately, we are witnessing such incidents because there are no concrete measures to ensure the implementation of laws to prevent violence against women."
Authorities meanwhile shut down the news website Rokna, saying it "psychologically disturbed society" after it shared the viral video of the man, IRNA reported.
