Aramazd Andressian Jr., affectionately known as Piqui, would have turned 6 years old on Monday.
MORE: South Pasadena honors slain 5-year-old boy with memorial bench
His mother, Ana Estevez, and the rest of her family are expected to attend a tree dedication at the Los Angeles County Arboretum and Botanic Garden in Arcadia Monday afternoon.
The young child disappeared last April while visiting with his father, Aramazd Andressian Sr., who later confessed to killing the boy.
Andressian Sr. was sentenced to 25 years to life in prison.
RELATED: Mom of slain 5-year-old South Pasadena boy talks about last moments with her son