What is the ruling on semi-premeditated killing, and what are its consequences in terms of blood money, expiation, or fasting, especially if there were four perpetrators who killed a person who assaulted them, and he died as a result of medical negligence?

Killing a soul which Allah has forbidden, except by right, is one of the gravest sins. In cases of quasi-intentional killing, sin is incurred by the perpetrator, and an aggravated blood money (Diyya) must be paid to the victim's guardians. Some scholars have also stated the obligation of expiation (Kaffarah), which is: freeing a believing slave; if one cannot find one, then fasting for two consecutive months. If the killers are a group, then each one of them owes expiation, and they owe one single aggravated blood money. However, if the slain person was a thief who entered their home and opened fire, then his blood is considered forfeit, and there is no guarantee for killing him because he was an aggressor.