Sierra Garcia, a United States citizen, was visiting his grandmother in Mexico City, Mexico at the time of his disappearance. On August 12, 2003, he was left alone in the care of a fifteen-year-old cousin. He was last seen with the cousin at 11:00 a.m.

When Sierra Garcia's other family members returned to the residence, they discovered that the cousin had been strangled and Sierra Garcia was missing. A ransom demand for 102,000 pesos, close to $10,000 in American money, was made for the baby's safe return. His family paid the money, but Sierra Garcia had not been returned to them. His case remains unsolved.

does not usually profile disappearances from outside the United States. An exception was made here because Sierra Garcia is an American citizen. The Federal Bureau of Investigation (FBI) in California is investigating his case.

Some agencies state that Sierra Garcia vanished from Ramona, Mexico.