Andy Jaiswal, 24, died early Saturday morning while working the overnight shift at Thornton's Gas Station in Streamwood.
Jaiswal's funeral was today. His family is demanding answers and justice.
"I know you're watching. You're one ruthless, heartless person," said Andy's cousin Pratima Jayswal. "You are going to be caught."
A masked man with a knife entered the gas station, stabbing Jaiswal to death before cleaning out the cash register.
Security cameras captured several images of the suspect, but his mask makes identifying him difficult.
Thornton's Gas is offering a $25,000 reward.