The son-in-law and cousin of Muhammad who was murdered after becoming caliph was Uthman ibn Affan. He served as the third caliph of the Rashidun Caliphate from 644 to 656 CE. Uthman's rule faced significant criticism and political unrest, ultimately leading to his assassination by rebels in Medina. His death marked a pivotal moment in Islamic history, contributing to the First Fitna, or civil war, within the Muslim community.
Umar (omar)
3rd caliph H. Usman ra was son in Law of prophet Muhammad saw .
Perhaps you are referring to abu Bakr? Abu Bakr was one of Muhammad's fathers-in-laws and became the first Caliph.
Caliph
They had ordered Abu Bakr to be a Caliph since he knew Muhammad.
Caliph (or Khalifa in Arabic)
Caliph refers to a Muslim civil and religious ruler, widely viewed as the successor of Muhammad.
Ali son of Abu Talib. Ali was the cousin of Prophet Muhammad and later became his son-in-law. He later became the fourth caliph of Islam.
Umar ibn al-Khattāb also known as Omar, was a friend of the Islamic Prophet, Muhammad, and one of his companions. He became the second Muslim ruler after Muhammad's death and ruled for 10 years
He was the third Caliph after Muhammad's death, and was killed by the Umayyads.
Caliph.
Caliph (or Khalifa in Arabic)