Florida authorities say they've canceled an Amber Alert for a missing 21-month-old boy and are investigating the disappearance of Lonzie Barton as a homicide.

The Jacksonville Sheriff's Office released surveillance video Monday showing the car of the mother's boyfriend, 32-year-old William Ebron, heading toward where the vehicle was eventually found abandoned and then Ebron running back toward his apartment.

Authorities say Ebron, who lived with Lonzie's mother, was caring for the boy and his 5-year-old sister when Lonzie disappeared July 24. Ebron initially told police he had left Lonzie in the car with its engine running while Ebron went into the apartment, and the car was gone when he returned.

Ebron is already jailed without bond on two counts of felony child neglect in connection with the case. Jail records don't list an attorney.