Iranian officials on Monday identified the gunman who opened fire at Shah Cheragh mausoleum last month, killing at least 13 people.
Iran's official news agency, the Islamic Republic News Agency (IRNA), reported that the gunman was a national of Tajikistan.
The gunman, identified as Sobhan Komrouni by IRNA, died in a hospital from injuries sustained during his arrest a few days after he opened fire at the Shiite shrine on October 26.
Shah Cheragh is among Iran's top Shiite shrines.
The attack added to tensions in Iran because it coincided with 40 days of mourning for the death of Jina Mahsa Amini, a day meant to mark the end of the traditional mourning period. Security forces also once again cracked down on protesters on October 26.
Afghan, Azerbaijani nationals also reportedly involved
IRNA said that the gunman's accomplice was an Afghan citizen, citing the Iranian Intelligence Ministry.
The news agency said a third suspect, from neighboring Azerbaijan, was allegedly the "main coordinator" of the attack. The Azerbaijani suspect reportedly met with IS operatives the Iranian capital of Tehran prior to the act.
Authorities arrested 26 suspects over the shrine attack as well, all reportedly nationals of Azerbaijan, Tajikistan and Afghanistan, the report added.
The so-called "Islamic State" (IS) claimed responsibility for the attack at Shah Cheragh last month. Officials had reported the gunman as being badly injured after being shot by the police.
CCTV footage broadcast on state TV last month showed the gunman entering the shrine after hiding an assault rifle in his bag. He then began shooting as worshippers tried to flee.
IS adheres to an extremist Sunni ideology. They have claimed previous violence in Shiite-majority Iran, including twin attacks on the Iranian parliament and the tomb of Islamic Republic founder Ayatollah Khomeini in 2017.
rm/wd (Reuters, AP, dpa)