The disappearance of a Virginia toddler and her mother is stirring up a lot of questions about the Amber Alert system.

Eight-month-old Chloe Johnson and Keir Johnson, 34, were last seen April 30 in Hampton, Virginia. However, an Amber Alert for Chloe was not sent out until May 11.

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Some people were curious why it took so long to trigger an alert.

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Hampton Police Chief Terry Sult said during a Friday evening press conference that an alert was not sent earlier because Chloe's case did not meet certain criteria.

He told reporters that Amber Alerts are not for all missing persons cases, instead they are reserved for abduction cases. Sult added that detectives were recently able to gather enough information for them to come to the conclusion that both Chloe and her mother, Keir, may have been abducted.

More Information: FAQ about Amber Alerts

Other people have had questions as to why no suspect information was released along with Chloe's Amber Alert. Sult said the information was purposely left out so it would not "harm" his detectives' investigation.

"It is extraordinarily important for the detectives to be able to control that information and to deal with anyone who may come into contact with them," he said.

Some people in the Washington area also received alerts about Chloe on their phones while others did not. According to the National Center for Missing and Exploited Children, a person's cell phone will receive an alert if it is within range to cellular carrier towers in the affected area.

While people can no longer opt-in or out of Amber Alerts, NCMEC said there are still some cell phones that can't hear the alerts that are sent out.