Volunteers had searched for days looking for the boy in tripled-digit heat, but on July 10, the body of the 11-year-old boy from Menifee was found in a shallow grave behind the family's home.
The memorial was arranged by the boy's father, Terry Smith Sr., who traveled to Southern California from his home in West Virginia. A spokesman told City News Service that the grieving father had to sell his only car to fund the trip from West Virginia.
A private service was held by the boy's mother this past weekend.
"Terry Jr. loved picnics and I want everybody to understand, this is one big picnic for everybody that helped search for him and that has been touched by him," Terry Smith Sr. said.
The memorial began at 6:30 p.m. at Lamb's Fellowship, 21901 Railroad Canyon Road, in Lake Elsinore. It was open to the public.
His 16-year-old half-brother is accused in the killing. He is being held at Southwest Juvenile Hall in Murrieta and is scheduled to make his next court appearance on Sept. 17. Prosecutors intend to request that he be tried as an adult.
City News Service contributed to this report.