Lex died an unexpected yet understandable death.
Recently, he had been muttering that something was coming, and would imitate the ringing of a phone.
But one night, while he was lying against the cell door as he mumbled to himself, he suddenly banged his head against it several times.
Then… he died.
It was normal for someone with a cracked head to die.
Lex didn't have any family; at least, none who could help hold a funeral for him.
Thus, the government spent Lex's money to help hold an expensive and extravagant funeral for him, and then buried him in a very expensive cemetery.
What was it like to sleep in a coffin worth hundreds of thousands of dollars and in a cemetery worth millions of dollars? Sorry, Lex didn't get the chance to experience it for himself.
On the day of the burial, Luke turned the guy's body to dust.