Are the funds that his brother collects from human trafficking permissible or forbidden?

It is not permissible to work in human smuggling because it exposes lives and properties to danger, contradicts Allah’s command to preserve life, and falls under throwing oneself into perdition, which is forbidden by His (the Most High) saying: "And do not throw [yourselves] with your [own] hands into destruction." (Al-Baqarah: 195). Any money earned from it is unlawful because it is in exchange for an illicit act and supports sin and aggression, which are forbidden by His (the Most High) saying: "And cooperate in righteousness and piety, but do not cooperate in sin and aggression." (Al-Ma'idah: 2). Furthermore, consuming unlawful earnings has severe consequences, such as not entering Paradise, prayers not being answered, and the heart becoming diseased or dying. However, if its owner repents and is poor and in need, he may take from this money what suffices his needs and expenses, even enough to purchase a lawful means of livelihood.