LOS ANGELES – The acquittal on Friday of a former fund-raising chief for Senator Clinton, David Rosen, can be traced to a series of strategic gambles taken by the prosecution – bets that ultimately failed to pay off.

After a trial that lasted more than two weeks, a federal jury deliberated for less than five hours before finding Mr. Rosen not guilty on charges that he caused the filing of false campaign finance reports in connection with a star-studded gala concert in August 2000 to benefit Mrs. Clinton’s Senate bid. Mr. Rosen was accused of reporting that the gala cost about $525,000, when the actual price tag was $1.2 million or more.

According to interviews with jurors, the prosecution’s case against Mr. Rosen was badly hurt by the decision not to call as witnesses two men intimately involved with the gala: a former Internet entrepreneur who bankrolled the event, Peter Paul, and the evening’s celebrity wrangling impresario, Aaron Tonken.

“We were all surprised,” juror Randall Hartland, 20, said, when asked about the failure to bring the two men into court.

Jurors were well aware of the role Paul and Tonken played in organizing the gala. Nearly every witness made reference to the men. In addition, defense attorneys showed jurors an ABC “20/20” broadcast that detailed how Paul rubbed shoulders with some of the hottest names in Hollywood and Washington before his publicly traded Internet company, Stan Lee Media, collapsed and he abruptly departed for Brazil.

During closing arguments, the lead defense attorney, Paul Mark Sandler, also called attention to the absence of Paul and Tonken. For good measure, the lawyer displayed large color photographs on a video projector in the courtroom.

Prosecutors have not publicly explained why Paul and Tonken were not called to the stand. However, an attorney familiar with the evidence in the case said it was because the two men have criminal records. Paul has a total of four felony convictions, the most recent of which is for stock fraud related to his tenure at Stan Lee Media. Tonken is serving a five-year prison sentence for fraud, which he committed in connection with celebrity-laden charity fund-raisers much like the Clinton gala.

The legal source, who asked not to be named, said the government feared that having the two men testify against Mr. Rosen would have led to hours of cross-examination about their histories. “It becomes a giant sideshow,” the source said.

Another concern for prosecutors was likely the sheer number of criminal witnesses the government would have been relying on if it had called Paul and Tonken. As it was, the government called two admitted lawbreakers to testify against Mr. Rosen. Adding Paul and Tonken to the mix would have brought to four the number of prosecution witnesses with criminal pasts.

Several jurors said a decision not to call one of Mrs. Clinton’s closest aides during the 2000 campaign, Kelly Craighead, also gave them pause.

“Where was Kelly Craighead?” asked juror Angelo Sanders, 29. One witness at the trial said that the night before the gala, he saw Ms. Craighead and Mr. Rosen arguing “pretty hard” over the scope and cost of the event. Another witness placed Ms. Craighead at a meeting where Mr. Rosen allegedly said he didn’t want to know about thousands of dollars in travel costs for singer Olivia Newton John to attend a Chicago fund-raiser for Mrs. Clinton earlier in 2000. Mr. Rosen said both accounts were false.

In court, neither side explained why they failed to call Ms. Craighead. Presumably, her testimony would have cut both ways. In his closing argument, prosecutor Peter Zeidenberg suggested that the defense was hiding something by not calling Ms. Craighead. However, jurors held her absence against prosecutors, noting correctly that the government had the burden of proof beyond a reasonable doubt.

Some jurors were also suspicious about a decision not to play a secretly recorded audiotape of Mr. Rosen made by a witness who was an FBI informant, Raymond Reggie. Reggie, who is a brother-in-law of Senator Kennedy, made the tape over a steak dinner with Mr. Rosen in 2002. The tape, which contains neither a smoking gun nor clear evidence of Mr. Rosen’s innocence, was excluded from the trial at the request of prosecutors.

The prosecution dwelled on relatively minor expenses they said Mr. Rosen should have reported, such as a $9,300 hotel bill and his use of Tonken’s Porsche 911 convertible for three weeks. Mr. Sanders, who works for a hip-hop music label, pointed out that the indictment alleged that Mr. Rosen knew that spending for the gala was “substantially more” than what was reported. “A $5,000 or $10,000 hotel bill isn’t substantial when you’re talking about $1.2 million,” the juror said.

Still, jurors were not convinced that Mr. Rosen, who testified in his own defense, was altogether innocent. “We don’t think he was a dove,” Mr. Sanders said. “I think everyone lied.”

“Something definitely happened here. There’s no doubt,” the jury foreman, Michael Johnson, 40, added.