Former Philadelphia Police Inspector Daniel Castro, whose federal extortion trial last month ended with jurors deadlocked on most of the charges against him, is headed back to court.

Federal prosecutors announced Thursday that they would seek to retry Castro on the charges on which jurors could not reach a verdict, including allegations that he plotted to hire strong-arm enforcers to collect a $90,000 debt he was owed by a former business associate.

During the trial, Castro argued that the government entrapped him by using FBI informant Rony Moshe to help him plot the extortion. Jurors sided with Castro and voted 10-2 in favor of acquittal on eight of the 10 counts against him. He was convicted of lying to the FBI and acquitted on an unrelated extortion charge.

Several jurors said in interviews afterward that they believed Castro was set up, with one juror stating she did not believe the case should have even been brought to trial.

Federal prosecutors declined to comment Thursday on their decision to retry Castro. Castro's attorney, Brian McMonagle, said that he would mount "a vigorous defense" but declined to elaborate. Trial is set for Aug. 22.

Few cases prosecuted by the U.S. Attorney's Office end in hung juries, but many of those that do are retried, according to spokeswoman Patricia Hartman.

Former Philadelphia police officer Malik Snell, for example, was charged with robbing drug dealers at gunpoint and brought to trial three times. Jurors deadlocked twice before Snell was convicted in 2007.

Castro, a 25-year veteran of the department, was indicted last November and swiftly fired. Before his arrest, he was seen by some as a rising star, and had said he had ambitions to become police commissioner.

The case against Castro was built with help from Moshe, the FBI informant who recorded conversations between himself and Castro as they discussed the extortion plot. No shakedown actually took place, but Moshe, acting at the government's behest, led Castro to believe one did.

Jurors heard numerous recorded conversations between Castro and Moshe, including an exchange in which Castro authorized the enforcers to "get rough."

On the witness stand, Castro admitted that he agreed to allow the enforcers to use violence to collect his debt, but said he was talked into it by Moshe, whom he had considered a friend.

In highly emotional and at times tearful testimony, Castro expressed remorse and said he never would have broken the law if Moshe had not raised the idea. Castro accused the government of sending the informant after him, and described his involvement with the plan as "the biggest mistake of my life."

Defense lawyer Chris Warren expressed surprise at hearing that Castro would be retried.

"This man's career is over, his life is over," Warren said. "Castro is destroyed. The guy did something wrong, but how much blood do they want from him?"

To prepare for a retrial, Warren said, federal prosecutors would likely pore over the trial transcript to try to get rid of any tactics that they believed posed problems. Jurors may have been bothered by Moshe, whose testimony during trial sometimes contradicted earlier statements he made to authorities.

Warren said the jury may have seen the case as flawed from the beginning.

"It seemed that they took advantage of someone who was at an extremely vulnerable point," he said. "I don't think it's the government's job to see how long someone can resist temptation, or to see how far they can push someone."

Defense attorney and former federal prosecutor Rocco Cipparone Jr. said a retrial offers the prosecution the chance to anticipate the line of defense, as well as the ability to plug any holes in the case that emerged the first time around. The prosecutors may also rethink matters such as their jury selection process.

"This was a tremendous result for the defense," Cipparone said. "This was perceived as a high-profile loss for the U.S. Attorney's Office, and they don't like to lose."

If Castro takes the stand again, Cipparone said, the challenge for him will be to connect with the jury as strongly as he seemed to during last month's trial.

"It's hard to re-create that testimony," he said. "The question is: Will he be able to duplicate that emotion?"

Contact staff writer Allison Steele at 215-854-2641 or asteele@phillynews.com.