Source: Alabama hostage taker's declining mental state led to rescue

Midland City, Alabama (CNN) -- The rescue of a kindergartner from the underground bunker where he had been held for almost a week was precipitated by concerns the kidnapper's mental state was in sudden decline, a law enforcement source close to the investigation said Tuesday.

Authorities have said little publicly about the Monday rescue that killed 65-year-old Jimmy Lee Dykes and freed his 5-year-old captive just two days before the boy's birthday.

But the law enforcement source said Dykes' mental state deteriorated in the 24 hours before the Monday afternoon rescue, and experts from FBI units, including a crisis negotiation team, tactical intelligence officers and a behavioral sciences unit, determined he was in a downward psychological spiral.

The FBI's hostage rescue team forced its way into the bunker and rescued the boy, the source said.