What is the ruling on dealing with a brother who suffers from schizophrenia, commits apostasy, insults religion, disobeys his parents, commits adultery, drinks alcohol, and threatens to kill his mother and then commit suicide, and what is the ruling on the father's desire to kill him to be rid of him?

What this brother is doing, from abhorrent crimes to killing his mother and himself, is among the grave sins. It appears he is suffering from a mental illness, and therefore, the pen is lifted from him, as the Prophet, peace and blessings be upon him, said: "The pen is lifted from three: from the sleeper until he awakens, from the child until he reaches puberty, and from the insane person until he regains his sanity." You must seek treatment for him from psychiatrists, perform ruqyah (Islamic exorcism) for him, and supplicate for him. There is no objection to seeking assistance from the authorities to curb his evil. As for what the father desires, which is to kill him, it is not permissible Islamically. He can be gotten rid of by expelling him from the house, not by killing him.