A political operative who worked on the election bids of prominent New York Republicans was convicted Friday of cheating Mayor Michael Bloomberg out of hundreds of thousands of dollars, ending a case that has put a spotlight on the billionaire mayor and the inner workings of his campaigns.

John Haggerty remained expressionless, occasionally blinking, as he was found guilty of second-degree grand larceny and money laundering. Haggerty, who was acquitted of first-degree grand larceny, faces up to 15 years in prison at sentencing.

The 42-year-old was accused of promising the mayor's 2009 campaign an elaborate $1.1 million poll-watching operation, then spending just $32,000 on the effort and pocketing most of the rest to buy a house.

In the end, jurors were unconvinced by defense lawyers who often tried to turn their attention to the mayor, painting a picture of a former mogul who threw his money at problems and surrounded himself with highly paid insiders so desperate to hold onto power that they didn't care how Haggerty spent the money he was given, as long as he got results.

Jurors recounted tense deliberations that had begun with the panel evenly split on whether to convict, with some panelists swayed by the defense's depiction of a high-rolling, win-at-all-costs campaign.

"There was a lot of talk in the jury room just about conspiracy," juror Stephen Conroy said. "Just that everybody was in on it, Haggerty was the fall guy."

Prosecutors maintained the mayor was the victim in a simple but lucrative scam: Haggerty, assigned to handle poll-watching for the campaign, drew up a budget to pay more than 1,300 watchers, hire drivers and rent hotel rooms. Once the mayor had donated money to the state Independence Party to pay for the effort, Haggerty created a company through which to launder the money, and used $750,000 to buy a house. On Friday, state Supreme Court Justice Ronald Zweibel ordered him held on $250,000 bail.

The four-week trial lifted a veil from Bloomberg's private and political dealings. His 2009 campaign manager conceded on the stand that he had worried Haggerty's operation could look bad to the public. A former deputy mayor told jurors that he hadn't enjoyed his first two years at City Hall because he found it more difficult to get things done there than at Bloomberg's eponymous financial information company. Bloomberg's top city deputy and longtime confidante detailed how she was authorized to spend the mayor's vast personal funds.

And the mayor himself took the stand, speaking calmly and precisely even as a defense attorney raised his voice, pointed his finger at him and came close to calling him a liar. To the defense's questions, Bloomberg said repeatedly that he could not remember the answers. Among the things he could not recall: $1.2 million in additional donations to the Independence Party the year before Haggerty entered the picture.

"For months the defense has attempted to cast aspersions on Mayor Bloomberg and make him the focus of this case," Bloomberg spokesman Jason Post said in a statement. "We are pleased that the jury saw through their cynical efforts and reached a verdict based on the evidence and the law."

The defense contended that the mayor's campaign _ which cost the billionaire more than $100 million _ had tried to distance itself from Haggerty's so-called ballot security project by arranging for Bloomberg to pay for it through the Independence Party _ a contribution that wouldn't be reported until after the election.

Democrats in New York and elsewhere have long said that such operations are a cover for voter suppression, often in precincts with large minority populations. On the stand, the mayor _ who narrowly won the 2009 race against then-city Comptroller Bill Thompson, who is black _ said he believed the ballot security effort was meant to ensure that voters didn't encounter problems at the polls, and paying for it through the party was simply standard procedure.

Defense lawyers had claimed that the arrangement meant that Bloomberg lost control of the money when he made the contribution, and argued that meant jurors couldn't find the money had been taken from the mayor _ a key assertion in the prosecution's case. It was an argument that jurors appeared to wrestle with, sending three separate notes to the judge over the course of three days of deliberations asking him to clarify whether they must find that the mayor was the victim and whether they were required to take the identity of the victim into account.

Ultimately, Conroy said, jurors concluded that in this instance Bloomberg had made the Independence Party his agent, meeting the legal threshold for the verdict. Dennis Vacco, Haggerty's lawyer and a former state attorney general, said that conclusion raised election-law concerns. The mayor has said his campaign did nothing wrong.

The hours of testimony by politicos and the glimpses of the back-room work of campaigns left jurors saying they had received an education in the realities of politics.

"There's so much money being thrown around, but it's very broad-stroked. No one looks at details or digs down, and I found that fascinating," Conroy said.

Juror Piper Gray said that after starting the trial with no opinions on politics, she left it knowing exactly where she stands.

"Now I'm probably never going to donate to a campaign," she said.

Michael Boice left the experience with more equanimity.

"I don't know if it's shady," he said. "There's a system that's set up, and people find a way not to get around the system, but they found a way to work within the system that they have."

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Samantha Gross can be reached at www.twitter.com/samanthagross