The reward for information in the shooting death of a pizza delivery driver in St. Louis is now up to a possible $15,000.

Police are investigating the death of 31-year-old David Matthews, who was delivering pizza for Imo's Pizza on July Fourth when he was shot twice in the neck. He died on Sunday

The St. Louis Post Dispatch reports Imo's family announced Tuesday it is donating $10,000 to CrimeStoppers to honor Matthews. That increases the reward fund to a possible $15,000 because the anonymous tip line generally offers up to $5,000 in homicide cases.

Police have not arrested any suspects in the case and have not discussed a motive.