Theories around what may have happened to Mojtaba Khamenei, successor to his slain father Ali Khamenei as the Supreme Leader of the Islamic Republic of Iran, gained ground as he has not appeared at the funeral ceremony of the father.A mourner weeps during the funeral ceremonies for slain Iranian Supreme Leader Ayatollah Ali Khamenei and members of his family at the Imam Khomeini Mosalla Grand Mosque in Tehran, Iran. (Altaf Qadri/AP Photo)Three other sons of Ayatollah Ali Khamenei, who was killed in US-Israeli strikes on February 28, prayed beside the coffins of their father and four other family members on Sunday. State TV showed Mostafa, Meysam and Masoud Khamenei praying near the coffins laid out in the vast courtyard of Tehran's Imam Khomeini Grand Mosalla, a sprawling religious complex, news agency Reuters reported.Masoud Khamenei was seen crying and wiping his tears with a keffiyeh — the chequered scarf that is a symbol in Iran of militant revolutionary ideals and solidarity with Palestinians — as an imam recited funeral prayers.The regime is holding a week of mass funeral processions for Ali Khamenei, including taking his remains to Shi'ite (Shia) religious sites in neighbouring Iraq. After a day of lying in state indoors for senior Iranian leaders and foreign officials to visit, Ali Khamenei's coffin was displayed outdoors on Saturday under glass. The coffins of his daughter, son-in-law, daughter-in-law and 14-month-old granddaughter were laid out next to his.Where is Mojtaba?There has still been no public sighting or realtime image released of Mojtaba, who is likely to have been injured in the attack that killed his father and the other family members when Israel and the US bombed Iranian targets to start the war that effectively ended this month.Mojtaba Khamenei's face was disfigured and he suffered a significant injury to one or both legs, Reuters has reported citing unnamed people close to his inner circle.A ceasefire has at present suspended the four-month-old war under an agreement with Washington. Iran's authorities say the deal will bring the country huge economic benefits, in what they describe as a victory over a superpower.US President Donald Trump told the news website Axios that peace talks had been paused for a week for the events surrounding the funeral.On Sunday, Iranian President Masoud Pezeshkian and Parliament Speaker Mohammad Baqer Ghalibaf prayed behind the coffins.Large crowds, ceremoniesCrowds of Iranians, many weeping and some beating their chests, have thronged the Mosalla. The Iranian metro railway network said it had clocked 7 million trips from late on Saturday to Sunday morning as people flocked to the centre.After what authorities are billing as a massive procession in central Tehran on Monday, the remains will be taken to the seminary city of Qom, the centre of Iran's Shi'ite hierarchy, for ceremonies on Tuesday.From there the body will be flown to Iraq for ceremonies in the Shi'ite holy ⁠shrine cities of ​Najaf and Kerbala on Wednesday. It will return to Iran on Thursday for another ​procession in Mashhad, to be buried near the tomb of another of the medieval Shi'ite imams.Authorities plan to mobilise millions of people for big processions over the coming days, offering transport, food and lodging.(Reporting by Reuters staff in Tehran and Nayera Abdallah and Tala Ramadan in Dubai; Writing by Raju Gopalakrishnan; Editing by William Mallard)