One juror, Randy Hartland, 20, of Torrance, said after Friday's verdict that he found it difficult to believe that Tonken and Paul were innocent pawns.
He also questioned the credibility of two Democratic Party fundraisers who worked on the gala and testified against Rosen.
James Levin, a Chicago businessman, said Rosen was alarmed about the mounting costs but told him privately, "The costs of this event will not be the cost of this event." Rosen denied saying that.
Levin testified a few days after he agreed to plead guilty to federal bribery, fraud and conspiracy charges. He said he hoped for a lighter sentence because of his cooperation with Rosen's prosecutors.
Also testifying against Rosen was Raymond Reggie, a member of a politically prominent Louisiana family whose sister is married to Sen. Edward M. Kennedy (D-Mass.). He said Rosen confided that he was being "crushed" by spiraling last-minute spending for the fundraiser. Reggie is awaiting sentencing after pleading guilty to federal bank fraud and check kiting charges.
The jury foreman, Michael Johnson, 40, of Los Angeles said the case came down to reasonable doubt.
"This was largely a paperwork case," he said. "We tried to follow the money. But there were so many people involved that it was hard to pin down who was responsible."
The jury rendered its verdict after five hours of deliberations over two days.
One leading expert on campaign law said after the verdict he was surprised that the government brought criminal charges against Rosen instead of resolving the violation through civil action and fines, if warranted.
"Frankly, I was quite surprised that they brought a criminal case," said Robert M. Stern, president of the Center for Government Studies in Los Angeles and former general counsel of the California Fair Political Practices Commission.
Justice Department officials could not be reached for a response.
Rosen, 38, who lives in Chicago, said he plans to resume his career as a political consultant.
Times staff writer Maura Reynolds contributed to this report.
