The incentive went up Tuesday for possible witnesses to come forward after a Marietta teenager was shot to death during a large party earlier this year.

Marietta police have been investigating the death of Grayson Green since May 21. The 17-year-old was shot and killed in the parking lot at the Walton Village apartments in the 1600 block of Roberta Drive.

Crime Stoppers of Atlanta offered a $2,000 reward in the wake of the shooting, which was matched by Walton Village and Walton Communities, the apartment complex’s property management company. Both organizations upped the ante and collaborated to increase the reward to $10,000, police said in a news release Tuesday.

According to investigators, a large group of teens and young adults was at the apartment complex for an unsanctioned party after leaving an Airbnb home. Gunshots interrupted the late-night shindig.

Police released surveillance footage that showed the crowd of about 20 people fleeing the area as officers arrived to find Green lying on the pavement near the gated entrance. The teen had been shot in the chest. He was taken to Wellstar Kennestone Hospital, where he died, police said.

Now investigators are hopeful some of the partygoers who fled the scene will come forward to help police find those responsible for Green’s death.

Anyone with information is asked to call the Marietta Police Department’s tip line at 770-794-69900. Tipsters can remain anonymous, and be eligible for the $10,000 reward, by contacting Crime Stoppers Atlanta at 404-577-8477, texting information to 274637 or visiting the Crime Stoppers website.