TALLAHASSEE, Fla. -- Bob Butterworth resigned Tuesday as the head of Florida's historically troubled child protection agency, following a 19-month stint in one of the toughest jobs in state government.

Butterworth, a Democrat who served as Florida's attorney general from 1987-2003, led the Department of Children and Families since being chosen for the job in one of the first appointments announced in December 2006 by incoming Republican Gov. Charlie Crist.

Butterworth plans to go into private practice in South Florida. He had initially told Crist that he would take the DCF job for a year and a half. The resignation is effective Aug. 15.

"This, I believe, has been the greatest challenge and the most rewarding challenge," said Butterworth, who has also served as a Broward County prosecutor, judge and sheriff, mayor of Sunrise and head of Florida's Department of Highway Safety and Motor Vehicles over his career.

"The governor tried to keep me here, but I think it's the right time," said Butterworth, adding that he's urged Crist to choose his successor from within the agency.

Butterworth's performance at DCF was widely applauded Tuesday.

"Under General Butterworth's leadership, Florida saw its first significant decline in entries into foster care since 1998 with no compromise of child safety," said Richard Wexler, executive director of the National Coalition for Child Protection Reform. "He understood it is only common sense that there can be no child protection without family preservation."

Butterworth also sought to restore morale in an agency often in the news for mismanagement or malfeasance.

"Because of his tenure there, the public has a much better understanding of the challenges that any human services director faces," said Kate Kearney, who led DCF from 1999-2002 and has known Butterworth for 25 years. "He tackled the confidentiality issues and lobbied hard for changes in the law that would allow transparency."

Butterworth's immediate predecessor, Lucy Hadi, resigned after being found in contempt of court for not moving inmates to state hospitals if they were found incompetent to stand trial.

Before that, Jerry Regier left the position after an investigation showed he accepted favors from contractors.

Butterworth resolved hundreds of pending lawsuits during his brief tenure at DCF, including the court standoff inherited from Hadi, and embraced Crist's push to make state government more transparent.

"In order for people to have a real trust in government, they have to be able to see what's going on, especially in agencies like this," Butterworth said. "We have literally opened up this agency and in many cases have gone to court to get records released."

George Sheldon, the agency's assistant secretary, predicted the 65-year-old Butterworth will stay active in public policy.

"I think he'll stay involved in shaping a lot of child welfare and mental health issues," Sheldon said.

But political office, Butterworth said, is not likely in his future.

"I don't see it happening," he said, adding, "I thought I'd closed the door a couple times before."

Butterworth, who lost a bid for a state Senate seat in 2002, faced his share of controversy during his time at DCF.

Former agency spokesman Al Zimmerman -- hired under the Hadi administration -- disgraced the agency earlier this year after he was accused of taking nude photos of at least two teenage boys for distribution to overseas pornographers. One of them was identified as a foster child in DCF's care.

DCF had not done a criminal background check before hiring Zimmerman, who pleaded not guilty to a charge of producing child pornography. After Zimmerman's arrest, the agency did an expansive review of its personnel files, finding that about 1,300 employees were missing some information, such as a background check.

The department was also criticized last year for losing track of a 2-year-old foster child, whose disappearance wasn't reported by child protection workers for four months.

The girl, Courtney Clark, was eventually found in Wisconsin along with three other endangered young children. A severely injured and malnourished 11-year-old boy was found hiding in a closet.

Courtney's mother, Candace Clark, and other adults were also in the house. The 11-year-old boy's mother was found dead at the home, buried in the yard.

In 2002 under Kearney's watch, the department discovered that Rilya Wilson, a 4-year-old Miami foster child, had been missing for more than year, and her caseworker had lied about visiting the home. The girl was never found and her caregiver has been charged with murder. The caseworker was fired and pleaded guilty to official misconduct, getting probation.

This year Butterworth announced that child welfare workers would carry handheld GPS devices to electronically update case information during home visits.