He also has less to lose, they say. Even if Williams brings charges and fails to win convictions, he could argue that Kane disparaged the case so widely that he could not salvage it.
"There is always an element of risk, but it seems to me he is pretty confident," pollster and political analyst G. Terry Madonna said of Williams. "It's still hard for me to figure out why Kane turned this case over to him."
Kane, a Democrat, has criticized the sting, which was run under three of her Republican predecessors, as poorly run, and possibly tainted by racial profiling. The five elected officials caught on tape are African American.
While Kane said the investigation had revealed crimes, she said its flaws precluded a successful prosecution.
Among her criticisms was that the investigation lacked evidence of a "quid pro quo." In some instances, she said, the legislators were offered money to vote for legislation they already supported.
She has also said that the credibility of the sting's undercover operative, Tyron Ali, was irreparably damaged: Ali had been facing charges in an unrelated fraud case and was offered what she called "the deal of the century" by her predecessors who dropped 2,088 counts against him in return for his cooperation.
Kane secretly shut down the case shortly after taking office in January 2013. After The Inquirer revealed the aborted probe in a March 16 story, Kane publicly assailed the case.
Among those who questioned her decision to abandon the investigation in midcourse was Williams, who said it appeared to be a solid case.
Kane subsequently challenged him to take up the investigation. He readily accepted and asked for the file, which Kane's office turned over on Wednesday.
Williams' spokeswoman, Tasha Jamerson, declined to comment Friday except to say that the case would be treated "like any other case the office handles." She said the office did not comment on cases in which charges had not yet been filed.
Among the issues that Williams has to decide in coming days is whether his office should use the work done by the state prosecutors, or do additional investigation, possibly even empaneling a grand jury.
Williams also must navigate some tricky territory, as the lead prosecutor in the state's sting investigation, Frank G. Fina, now works for him in the anticorruption unit of the District Attorney's Office.
The Philadelphia Democrats captured on tape either declined to comment or could not be reached Friday. They are State Reps. Ron Waters, Vanessa Brown, Michelle Brownlee, Louise Bishop, and former Philadelphia Traffic Court Judge Thomasine Tynes.
Bishop has denied taking money from Ali. Brownlee said she could not recall accepting anything from him. Brown has declined to comment but through her lawyer has denied wrongdoing. Waters said he might have received something from Ali for his birthday.
Tynes has acknowledged receiving a bracelet from Ali but has denied any wrongdoing.
Should Williams decide that the evidence warrants criminal charges, some veteran defense lawyers said, he might look to offer deals to the officials - possibly offering them probation in return for guilty pleas and resignations from office.
As a sweetener, some lawyers said, prosecutors could select a crime for the plea that would not trigger a loss of their state pensions.
Thomas Bergstrom, a former federal prosecutor and veteran Philadelphia criminal defense lawyer, said he believed Williams could obtain convictions.
Asked about Kane's suggestion that the targets had been unfairly selected, possibly for racial reasons, Bergstrom said defense lawyers would have to persuade judges to permit that allegation to be aired before a jury.
And unless the evidence of racial bias was strong, Bergstrom said, judges would likely deem it inadmissible. "That's a very, very high burden to meet," he said.
Bergstrom also said that despite Kane's assertion the evidence of a quid pro quo was weak, that wouldn't necessarily deter a jury from convicting.
"There's another side to that coin," he said. "Why is this guy handing out money if he doesn't expect something in return? And why were they taking it?"
As for the non-prosecution deal struck with Ali, Bergstrom said: "Prosecutors give deals all the time."
He added: "I haven't understood why a good prosecutor couldn't bring that case and win it."
Walter Cohen, a former acting state attorney general, said Williams' review of the sting evidence was not without challenges.
Among them: What charges, if any, to bring?
Cohen said he believed it would be difficult to make a case for bribery since Ali, the undercover operative, was offering money ostensibly in return for votes against a controversial bill requiring voters to show identification at the polls. Every Democrat in the state was against that bill, Cohen said.
He also said a jury might be skeptical of the relatively small amounts of money Ali offered elected officials. "A jury may look at it and say: 'Is this all there is? Someone took $500 and didn't report it?' " he said.
Cohen and others said defense lawyers would be sure to point out that state law permits lawmakers to accept cash gifts of any amount - and in the case of Tynes, a $2,052 Tiffany bracelet - as long as they report it on their annual financial-disclosure forms.
The five Philadelphia Democrats did not report the money or gifts.
Of the five who accepted money or gifts from Ali, Waters took the most, according to interviews and documents, including an official day-by-day summary of the investigation obtained by The Inquirer.
Waters accepted a total of $8,250 in eight payments, the summary says.
According to the summary, Ali initially made no demands of Waters. Before long, however, Ali allegedly was giving Waters cash and asking him for help landing government work. Waters obliged, according to the summary, helping set up a meeting with the head of a Philadelphia agency.
Reached for comment late last week, Waters said he would not discuss the tapes. He said he had a lawyer but would not say who he or she was.
Brown received $5,000 in six payments from Ali, according to the summary. With some of the payments, Ali allegedly sought to tie those payments to her vote on the voter ID bill.
As it turned out, the voter ID bill was one of Ali's chief talking points in the sting. He pressed all four of the state representatives to vote against it.
Critics, including former Gov. Ed Rendell, have said it made no sense to pay the lawmakers to vote for something they supported in the first place. Sources say prosecutors deliberately chose the voter ID bill because they did not want to influence the natural outcome of legislation.
According to the summary, after giving Brownlee $2,000 in cash during a walk one evening in June 2011, Ali later told her over dinner that he was focused on the voter ID measure.
"I'm definitely against that bill," Brownlee said, according to the summary.
"Thank you so much," Ali replied.
Ali made three payments to Bishop, totaling $1,500, according to tape summaries. He never urged a vote on any specific measure during the meetings in which payments were made, the summaries show. But at other meetings, he urged her to vote against the voter ID bill, and they discussed other legislation, including a measure to privatize state liquor sales, according to the documents.
As for Traffic Court Judge Tynes, Ali gave her the bracelet after lobbying her to help him get a contract collecting fines for Traffic Court, according to the tape summaries. Tynes, before being given the bracelet, made a call on Ali's behalf to the administrative judge of Traffic Court, according to the summaries.
While Williams declined to speak for this article, he has left little question about where he stands.
In an op-ed that appeared in The Inquirer, he derided Kane's assertion that she could not prosecute the sting case. He also mocked Kane's position that Ali's credibility was damaged because of the deal he struck with prosecutors.
"Prosecutors around the country - local, state and federal - regularly and successfully bring cases based on the testimony of some very bad men, sometimes even men who have been granted complete immunity after committing multiple murders," wrote Williams.
"But the Attorney General of Pennsylvania drops a case supported by hundreds of hours of devastating tapes, because the main witness got a deal on a bunch of government fraud charges."
For a month now, Kane has publicly criticized the case. At one point, she referred to the investigation as "half-assed."
When Williams raised his criticism, she suggested he take up the case, saying: "Bring whatever charges you believe to be appropriate."