EVERETT — Snohomish County Executive Aaron Reardon on Thursday said he is the victim of an “appalling charade” after the Washington State Patrol announced it is investigating his use of public money.

The investigation focuses on Reardon’s spending on out-of-town trips, and the questions were brought to county prosecutors by a member of Reardon’s own political party.

Reardon on Thursday denied any wrongdoing. The Democrat, looking confident, questioned the timing of the allegations becoming public just days before Tuesday’s election. He accused the campaign and supporters of his Republican opponent, state Rep. Mike Hope, who is trying to keep Reardon from winning a third term.

“We haven’t done anything wrong,” Reardon said during a press conference. “We have checks and balances” in Snohomish County.

Word of the investigation left many people wondering about the potential impact on an election that already has seen plenty of mud-slinging.

“For both campaigns, this is the capstone of a very ugly race,” said Christian Sinderman, a Democratic political consultant. “It doesn’t make anybody look good.”

A Washington State Patrol spokesman on Thursday confirmed the probe after being questioned by reporters, who had been contacted by Hope’s campaign.

“We are doing a criminal investigation of what we would characterize as an allegation of a possible misappropriation or misuse of public funds. We were asked to do that by the Snohomish County prosecutor,” State Patrol spokesman Bob Calkins said.

The investigation was launched at the request of Snohomish County Prosecuting Attorney Mark Roe, who is also a Democrat.

Roe declined to offer details of what exactly is being investigated.

“It is my strong belief that no decisions or conclusions can or should be made until the facts are known,” he said in a prepared statement.

In response to a public records request from The Herald, Roe on Thursday released a copy of the Oct. 26 letter he sent State Patrol Chief John R. Batiste requesting the investigation.

The allegations were of sufficient gravity that they could constitute official misconduct and required close scrutiny, the prosecutor wrote.

“This is a highly sensitive situation, since even the existence of an investigation could have significant impacts on the individuals involved, and even on county government as a whole,” Roe wrote. “Yet, without a professional investigation we can’t know whether or not any wrongdoing took place. It is, therefore, my opinion that the facts of what did or did not take place must be conclusively determined as soon as possible.”

Calkins declined to provide specifics about the patrol’s investigation.

“We are just getting into it at this point,” he said.

Reardon said no investigators had contacted him or his office.

“If it isn’t coming from the Hope campaign or someone associated with his campaign, I would apologize” for blaming them, he said.

Evidence points both directions. Hope’s campaign in recent days has been contacting reporters, suggesting that an investigation was focusing on Reardon. At the same time, there is evidence the complaint about Reardon reached prosecutors through a leading county Democrat.

County Council Chairman Dave Somers said his office forwarded concerns about Reardon to Roe. Somers said a person — he declined to offer more specifics — approached his office and shared concerns about the executive’s travel expenses using county money. He said that person was not connected to the Hope campaign.

“We became aware of some allegations and talked to the PA’s office, and they thought they were serious enough to turn over to the Washington State Patrol for an investigation,” Somers said. “They involve travel and expenditure of public funds, and if true — and we don’t know how much of it is — it rose to the level that I felt we needed to talk to the prosecuting attorney’s office and they thought it was serious enough to turn over for an investigation.”

Reardon and Hope have waged a fierce election battle, with attack ads and assaults on each other’s character.

Elected leaders expressed dismay that word of an investigation had become public just days after it commenced.

“The timing is really unfortunate,” Somers said. “I’m not sure how it got out, but I’d prefer that it were either way before, or way after, the election.”

Similarly, Councilman John Koster, a Republican, said he has grown wary of the various attacks against both candidates throughout the campaign for executive.

“It’s been too much about allegations on one side or the other and not enough about issues, which is unfortunate,” Koster said.

Reardon’s campaign, for example, has gone to considerable lengths to publicize a 2000 traffic stop in Mill Creek, in which Hope’s actions as a passenger led to a brief suspension from his job as a patrol officer with the Seattle Police Department.

For his part, Hope has been raising questions about what he calls management missteps by Reardon. For months, he’s questioned the executive’s travel expenses, including in campaign TV ads.

Hope accused Reardon of spending about $14,000 on a 2005 trip to the Paris Air Show. Reardon’s office, in response to a public records request, provided documentation showing the amount spent was closer to $3,600.

Hope said that even if the higher figure is off the mark, the lack of documentation for some of the expenses should raise questions about how the money was spent.

“It looked suspicious to me,” said Hope, who as a police officer has worked as a detective.

He called on the executive to provide itemized records for the overseas trips.

As to the State Patrol investigation, Hope said, “I hope for the people of Snohomish County that it’s not true.”

Hope also denied receiving any special tip-off from state troopers. Hope said he and campaign manager Jason Chambers knew about the allegations on Wednesday because troopers interviewed an acquaintance of Hope’s, who has previously raised questions about Reardon’s travel expenses.

“I don’t influence what State Patrol does,” Hope said. “I don’t have inside information about the State Patrol and who they’re investigating.”

Voting is under way in the all-mail election. As of Thursday morning, about 19 percent of the ballots mailed already had been sent back to the county auditor for tallying.

Noah Haglund: 425-339-3465, nhaglund@heraldnet.com.