The baby sitter and mother of a 7-month-old Florida girl missing for five days and then found alive in a box under the sitter's bed were charged Thursday in Shannon Dedrick's disappearance.

Last week, baby sitter Susan Elizabeth Baker asked the infant's mother Chrystina Lynn Mercer to give her custody and Mercer agreed, Washington County Sheriff Bobby Haddock said.

The baby was turned over on Saturday, the day she was reported missing, according to Haddock.

The sheriff said Baker and Mercer both were charged with several felonies, including interfering with child custody, false report of a crime, false report of a missing child and contributing to the delinquency of a child.

Baker also was charged with neglect of a child with aggravating circumstances; Mercer faces additional child desertion charges.

SLIDESHOW: Baby Shannon Found Alive

Baker already is suspected along with her husband James in the 1987 disappearance of her 3-year-old stepson Paul, who was never found.

On Wednesday night, authorities said they found the baby alive in a sealed 2-by-3-foot box hidden under Baker's bed in her Chipley home.

Shannon had been inside the box for almost 12 hours, Haddock told reporters Thursday afternoon, choking back tears.

"The baby had been fed, well cared for," he said. "There was no baby bottle in the box. This was a hiding place. She knew we were coming and would place her in the box."

Baker's husband James Arthur Baker was detained along with the women, but released after being questioned when police determined he wasn't involved, the sheriff said.

The child's father, James Russell Dedrick Jr., — who is related to Susan Baker — also wasn't charged.

Haddock called an unusual 1 a.m. press conference Thursday and told reporters he had "good news." He then went to another room with television cameras rolling and came back holding Shannon in his arms. People applauded.

"We are the proud papas of a little girl," Haddock announced. "This is Shannon Lee Dedrick. We found her safe."

Investigators discovered Shannon at 9:55 p.m. Wednesday in a box tucked under a bed surrounded by objects intended to hide the little girl at the Bakers' home in Chipley, the sheriff said.

The baby was placed in protective custody.

"Statistically speaking this should not have ever happened, that we found this child alive, especially after so many days. Time was against us," Haddock said.

Shannon was taken to a hospital but appeared healthy, according to Haddock.

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"It was very emotional for us, because once we got her to the hospital, we called our wives and every one of us was crying. Grown men crying. It's just such a relief," he said. "We've had missing children cases in the past, but nothing like this."

Haddock wouldn't provide details about the possible charges against Susan Baker, James Arthur Baker and Mercer or say how they believe the mother was involved.

The baby had been missing since Saturday morning. Her parents said they last saw her when in their rural Panhandle mobile home when they went to bed around 3 a.m. and investigators believe she vanished sometime between then and 8 a.m.

Her parents did not report her missing until after 11 a.m., but authorities have not explained the discrepancy.

About 100 law enforcement agents and others spent days scouring dense vines and marshes around the baby's home in a remote, makeshift community of dirt roads, tin-roof shacks and old mobile homes.

On Wednesday, investigators contacted the Bakers and asked to search their home, about 12 miles from where Shannon was last seen. They agreed and authorities found the baby there Wednesday night.

According to court documents, child welfare officials began looking into allegations Shannon was being abused less than two weeks after she was born.

In August, Susan Baker wrote a letter to Gov. Charlie Crist's office, pleading for help for the baby.

She claimed Dedrick shook Shannon and that he, Mercer and others smoked cigarettes and drugs in front of her. Baker also claimed Dedrick was not the child's father and said he claimed paternity to get welfare benefits.

Investigators frequently went to the infant's home from August to late September and reported that both parents used marijuana and kept a messy home.

But they said Shannon seemed to be cared for and in September, a physician determined that she was healthy and expressed "no concerns regarding the baby."

Susan Baker was involved in another missing child case in South Carolina more than two decades ago. She told authorities her stepson, 3-year-old Paul Leonard Baker, disappeared from the family's Beaufort, S.C., home on March 5, 1987, while she was napping.

A massive manhunt in the swampy area around the home turned up nothing. She and her husband, James Baker, were extradited to South Carolina in 2000 and charged with assault and battery in Paul's disappearance, according to police reports provided by the South Carolina Law Enforcement Division.

But a grand jury never indicted them and the child was never found.

Susan Baker did serve prison time after authorities investigating her stepson's disappearance discovered a 6-year-old girl in the Baker home believed to be Paul's sister had been badly beaten.

Baker was sentenced to 10 years in prison but the sentence was suspended after 80 days.

A sheriff's investigator from Beaufort County was sent to Florida to assist in the missing child case, spokeswoman Robin McIntosh said Wednesday.

Shannon's grandmother Kandis Boyer told the News Herald that she left her Texas home at 6 a.m. Tuesday with her two daughters and drove to Chipley.

“We’re taking this one step at a time,” Boyer told the paper. “The main focus is on Shannon. Thank God for bringing my granddaughter to safety.”

The Associated Press contributed to this report.