Joel and his brother Mario were last seen playing basketball at the Livingston Middle School playground in the 600 block of F Street in Livingston, California at 5:30 p.m. on March 8, 2005. They have never been heard from again. Their foster parents reported their disappearances to the police two hours later. Mario and Joel did not have any extra clothing with them when they went missing. Neither of them have histories of running away.

Joel, Mario, and their two sisters had been removed from the Madera, California home of their biological parents, Joel Hernandez Lopez Sr. and Ana Lopez (sometimes referred to as Anna Sandoval-Lopez), and placed in foster care shortly before the boys disappeared. Authorities have been unable to locate Ana and Joel Sr. since then and think it possible that Joel and Mario could be with their parents. Joel Sr.'s date of birth is January 11, 1960; he was forty-five years old in March 2005. Ana's date of birth is June 21, 1962; she was forty-two. Photographs and additional vital statistics for the parents are unavailable. Their last known address was in Fresno, California.

It has not been established that the Lopez brothers are with their parents and authorities are still uncertain as to what happened to them. They may still be in the Livingston area or may have returned to Fresno. Their cases remain unsolved.