The expression: “He’d steal the pennies off a dead man’s eyes” meant anyone who would do that had no scruples. Ray Hamilton, one of the Bonnie and Clyde gang members of the beginning of the 1930s, said before going to the electric chair for murder: "Bonnie and Clyde? They loved to kill people, see blood run. That's how they got their kicks. They were dirty people. Her breath was awful and Clyde never took a bath. They smelled bad all the time. They'd steal the pennies off a dead man's eyes." Also one of the Texas Rangers who took part in the ambush and killing Bonnie and Clyde stated, "They were the worst killers in the Southwest. We weren't about to take any chances with those two. Others did and they died. A lot of folks can rest easy now...even Bonnie and Clyde."
In the past when people were more superstitious they believed if a dead person’s eyes were left open to look on them would see their own death mirrored there. It is also believed that some cultures would leave coins on the eyelids of the deceased so that they could take money to their family members in the spirit realm.
There is another explanation of why money was put on the eyes of the dead. Charon’s obol, a coin of ancient Greece, was either placed over the eyes of a deceased or in the mouth for the ferryman who, according to their superstition conveyed souls of the dead across the river that divided the world of the living from the dead.