The complaint, alleging fraud and legal malpractice, was filed Tuesday in the city's Common Pleas Court. It seeks to recover $6 million, including the money paid to Chadwick.
"This approach reconciles the needs of the public with the realities of prosecuting a civil claim," Sprague wrote.
His statement came after the Committee of Seventy, a civic watchdog group, again called on Castille to release Chadwick's findings.
"As the highest judicial official in Pennsylvania, he has an obligation to at least explain his own involvement in what went wrong," the group's president, Zack Stalberg, said in a statement.
"A court case could take years," he said. "The 'new' Family Court could be old by the time it concludes."
Rotwitt was hired by the court system to push through a project to build a new courthouse for Family Court cases, including divorces, adoptions, and juvenile crimes. Rotwitt did so, helping to secure $200 million in state funds and a site at 15th and Arch Streets.
But that deal collapsed after The Inquirer reported in May 2010 that Rotwitt was also splitting development fees on the project with builder Donald W. Pulver.
Pulver is not named in the suit, and the court system paid him an additional $1.1 million for his development rights for the site.
Rotwitt has denied wrongdoing and says Castille knew what he was doing. Top lawyers at Obermayer, who fired Rotwitt a week after the story broke, say they had no idea he was getting paid on both sides of the deal.
On urging from Rotwitt, who said the deal might fall apart otherwise, Castille agreed to start paying fees even though no development deal had been signed. Those payments reached about $12 million before the deal was canceled.
