CAMDEN The prison-time arithmetic looks simple from the outside: Plead guilty, testify against others involved, and receive a shorter sentence.

In defendants' minds, however, the calculation can sometimes get unexpectedly complex.

"The two main things we see are, the person gets scared, or they have second thoughts because it's a family member or a cousin or something like that," said J.C. Lore, who teaches criminal law at Rutgers-Camden. "The fear is pretty real."

That scenario popped up recently when Kuasheim Powell, a gang member in Camden, entered a plea deal but then refused to follow through and testify against one of his nine codefendants - all now convicted in the Berkley Street double homicide from 2010.

The leader in the torture killings of Michael Hawkins and Muriah Huff, Powell took the deal in August 2011 - pleading guilty in the slayings as well as in an unrelated case of attempted murder, and agreeing to cooperate as needed.

But after going along with prosecutors during witness preparation, Powell suddenly said he would not testify in the 2012 trial of Clive Hinds, said Christine Shah, who led the case for the Camden County Prosecutor's Office.

Without Powell's testimony, said Shah, deputy section chief of the office's homicide unit, she was unable to get the sentence Hinds deserved. "In the end, obviously, I think it had a tremendous impact on the jury's verdict on the Clive Hinds case," she said.

Shah persuaded a Superior Court judge to vacate Powell's guilty plea and prepared to take him to trial.

This week, the Prosecutor's Office announced that Powell had struck a second deal, this time with a longer sentence - a total of 40 years in prison instead of the 30 he earlier negotiated.

"Thirty years is a significant sentence, there's no question about that at all. But at the same time, he didn't hold up his end of the deal," Shah said.

By then, the cases of Powell's nine codefendants were settled, with seven accepting plea bargains and two being convicted at trial.

"His opportunity to help us had passed," said Jason Laughlin, spokesman for the Prosecutor's Office.

Shah said she didn't know why Powell changed his mind.

Prosecutors were able to convict Hinds, one of three men who Powell said arrived with him at the home on the 500 block on Feb. 22, 2010.

When he initially pleaded guilty, Powell said he had brought a gun with him, gone upstairs, and found Hawkins bound and beaten.

Hawkins, 23, was targeted because of his involvement with the rival Crips gang, and because the Bloods believed he had stolen a bottle of liquor from them.

They beat him over several hours, breaking almost every bone in his face.

Powell told prosecutors he then shot Hawkins six times.

Huff, Hawkins' 18-year-old girlfriend, was downstairs. She was an innocent bystander, the Prosecutor's Office said, killed to prevent her from identifying her boyfriend's killers.

She, too, was beaten - attacked with a chair until it broke; stabbed; suffocated with a plastic bag; and strangled with a rope.

Hinds, against whom Powell refused to testify, was ultimately convicted of some charges.

A jury found him guilty of strangling Huff, but acquitted him of killing Hawkins. His murder conviction was automatically dropped to manslaughter after the jury agreed with Hinds that he had participated under duress.

Shah said Powell's testimony, as he had prepared it before refusing to cooperate, would have made clear that Hinds was his friend, not working under duress.

"We didn't have Powell to say, 'Yeah, we weren't pressuring anybody.' And I believe that's what his testimony would have said," Shah said. "They were tight, those two. But obviously that didn't come out with his testimony."

Hinds ended up with a 25-year term. Altogether, the 10 defendants have been sentenced to a total of nearly 300 years' time to be actually served, Shah said.

"It was a difficult prosecution because it was complicated. But in the end, the way everything worked out," Shah said, "I think everybody ended up with an appropriate sentence - with the exception, maybe, of Clive Hinds."

Powell's broken plea deal was one of two Shah encountered in the case. A 14-year-old suspect also reneged, and received a slightly tougher sentence. The two were the first broken deals she could recall in her 17 years with the Prosecutor's Office.

"If we enter into an agreement and we don't hold a defendant to his end of the bargain, then we lose credibility," she said.