Iran on Tuesday publicly hanged a convicted murderer at a square in the capital Tehran, local media reported.
The convict, Sajad Karimi, had confessed to shooting a doctor outside his practice in a populous eastern neighbourhood of Tehran a year ago.
The doctor, a cardiologist and university lecturer, died shortly afterwards of his wounds.
Karimi had said he planned the revenge attack on the cardiologist, who had been his mother's surgeon, following her death.
"I believed the doctor had made a mistake," Karimi was quoted as saying by Fars news agency moments before going to the gallows.
The hanging brings to 201 the number of executions reported in Iran so far this year, according to an AFP tally based on media and official reports.
Iranian media reported 179 hangings last year but international human rights groups say the actual number was much higher, ranking the Islamic republic second only to China in the number of people it executed in 2010.
Tehran says the death penalty is essential to maintain law and order, and that it is applied only after exhaustive judicial proceedings.
Murder, rape, armed robbery, drug trafficking and adultery are among the crimes punishable by death in Iran.