Four people have been arrested after an Iranian state prosecutor was shot dead outside his home in northern Iran.
Vali Hajgholizadeh, who officials say had a reputation for fighting corruption, was killed in the town of Khoy near the Turkish border.
Local officials said a Kurdish separatist group had claimed responsibility for the killing.
The region has been the scene of frequent clashes with Kurdish groups who want to establish their own state.
Two gunmen opened fire on Mr Hajgholizadeh outside his house late on Monday, and he died of his wounds in hospital.
The Free Life Party of Kurdistan (PJAK), a Kurdish militant group based in Iraqi Kurdistan claimed it carried out the attack, local government official Fakhrali Nikbakht told the Mehr News agency.
Four men were arrested on Tuesday, but no details have been given about their identities.
The Iranian state Press TV station reported Mr Hajgholizadeh had received death threats in the last few days.
A spokesman for the regional governor paid tribute to Mr Hajgholizadeh, saying he "had a brilliant record in battling land grabbing, moral corruption, and counter-revolutionaries".
PJAK was formed in 2004 and is affiliated to the Kurdistan Workers' Party (PKK).