IT WAS THE Brooklyn gangster's turn yesterday to spill the beans on his former pal, George Borgesi, the onetime Philly mob consigliere now facing a retrial in federal court on racketeering charges with his uncle, reputed mob boss Joseph Ligambi.

Anthony Aponick, a former New York mobster, shared a cell with Borgesi from August 2002 to September 2003 in a federal prison in Beckley, W.Va.

Prosecutors say that Borgesi, 50, stayed involved in a racketeering conspiracy - centered on sports betting, loan-sharking, extortion and video-poker machines - while in prison.

Aponick, speaking with a Brooklyn accent (offshaw for offshore), told jurors he became an associate of New York's Bonanno mob family at age 12. His father was Ukrainian/Lithuanian, his mom Italian-American.

For the mob, he collected debts. If people didn't pay, they would be threatened with violence, but it usually wasn't needed because they knew who backed him.

"I'm not a big guy, I'm a little guy," said Aponick, stout and dressed in a gray pinstriped suit. "I'm not imposing. You respect the dog for the master."

Aponick, who turned 42 yesterday, said under questioning by Assistant U.S. Attorney John Han that he was arrested in New York in 1997 for eight gunpoint pharmacy robberies. He pleaded guilty to one count each of robbery and a gun offense, and was sentenced to seven years and nine months.

In March 2002, he was sent to Beckley. There, he was introduced to Borgesi by a member of New York's Lucchese mob family.

"We seemed to hit it off. We laughed. We joked," Aponick said of Borgesi. Aponick learned that Borgesi was a high-ranking consigliere, or adviser, in the Philly mob. He cooked for Borgesi. They became such pals that in August of that year, Aponick became Borgesi's cellmate.

They became too close.

Aponick testified that after a while Borgesi started to tell him things that weren't public knowledge, like when a Philly mobster beat up a witness. He didn't want to know this stuff. He was nearing the end of his prison term.

So he got in touch with the FBI and became a confidential informant in September 2002. In return, the FBI paid him. And Aponick was able to get six months shaved off his prison term. A federal judge in New York granted the reduction after Zane Memeger, now the U.S. attorney in Philadelphia and at the time an assistant U.S. attorney, traveled to New York to ask for the reduction.

Unaware of Aponick's dealings with the FBI, Borgesi tried to lure Aponick to become part of the Philly mob, Aponick said. After Aponick's release from prison, Borgesi wanted him to move to Philly and make money by extorting bookmakers.

"Whatever you find out about, shake them down," Aponick said Borgesi told him. "He kept saying he needed 10-pack, he needed $10,000."

Aponick was the second cooperating witness to testify in this trial. Louis "Bent Finger Lou" Monacello, a South Philly mobster who became a government witness, testified in recent days.

In the first trial against Ligambi, 74, Borgesi and others, a jury acquitted Ligambi and Borgesi of some counts but deadlocked on others, triggering this retrial on the hung charges.

Prosecutors did not call Aponick to the stand at the first trial. As a felon, his credibility may be an issue.