DUBAI, United Arab Emirates—Iranian prosecutors opened criminal cases against six guards at the country’s notorious Evin prison, the judiciary reported on Tuesday, after footage showing the widespread abuse of detainees at the facility leaked out last week. The judiciary’s three-day investigation into mistreatment and grim conditions at Tehran’s Evin prison had landed “some” prison guards in detention, said judiciary spokesman Zabihollah Khodaeian. Authorities also summoned two guards and punished others, Khodaeian said, without elaborating on the penalties or identifying the suspects. The revelation comes days after The Associated Press published parts of the videos and a report about the abuse at the facility in northern Tehran, long known for holding political prisoners and those with ties to the West whom Iran uses as bargaining chips in international negotiations. An online account, purportedly by a self-described hacker group, shared footage of the incident, as well as parts of another surveillance video …