The guy who was wearing the seatbelt was well-restrained in the back seat. But the guy sitting next to him was unbuckled. The unbuckled man flew into the buckled man, and it is only a matter of luck which of the two skulls will crack. As luck had it that day, it was the buckled man's skull which cracked, leading to his death a few hours later.
> Please, always wear a seatbelt and make sure everyone riding with you wears a seatbelt.
Not only for their safety, but for your own safety as well!