Investigators digging into allegations that St. Paul City Council member and mayoral candidate Dai Thao’s campaign solicited a bribe are dealing with a hazy and seldom-prosecuted offense.

In the past five years, only one public official or employee was convicted under the state’s law against soliciting or accepting a bribe, according to state court data. Bribery prosecutions are rare in Minnesota because the state’s politics are relatively clean but also because bribery is hard to prove, said former Ramsey County Attorney Susan Gaertner, now in private practice.

“So much of it depends on not only what is said, and by whom, but what the context is, what nonverbal messages are being sent,” Gaertner said. “It’s very hard to reconstruct what happened.”

The allegations against Thao and his campaign manager emerged Saturday. The Minnesota Bureau of Criminal Apprehension (BCA) is investigating a February meeting between Thao, lobbyist Sarah Clarke and some of her clients, where they discussed a packaging materials ban the city is considering.

At the meeting, Thao asked them not to take notes, Clarke said, and asked for “resources.” It seemed clear he meant a campaign contribution, she said. Thao’s campaign manager, Angela Marlow, later texted Clarke saying, “Dai asked me to see if I could get a donation from your clients or yourself for his mayor campaign? My understanding is that they are leaving tomorrow. We will certainly rethink this issue.”

Thao declined to comment Tuesday. He has issued a statement saying he did not know of or sanction Marlow’s solicitation — a statement she refutes.

Clarke has worked in state politics for 11 years. She said this is the first time she has encountered a situation like this.

“There is a broad misconception that this stuff happens all the time, and that is absolutely not true and not the case,” said Clarke, who texted Marlow back saying the request could be “misperceived as a bribe.”

Marlow said Monday she thought the situation was a “miscommunication.” It was standard practice for her to ask for donations from people who asked for meetings related to issues in the mayoral race, Marlow said, and she didn’t know Thao could be voting on the issue as a council member.

Lobbyists typically give campaign contributions for access to the candidate, said Tom Heffelfinger, who was U.S. attorney for Minnesota during the prosecution of several Minneapolis bribery cases in federal court in the early 2000s.

“There’s a difference between access and quid pro quo, which is a promise,” Heffelfinger said.

Other people who have met with Thao, like local developer Craig Cohen, said they did not feel pressured to donate.

“It was a great dialogue. Not one iota of any solicitation of anything,” Cohen said.

Jeanne Weigum gave Thao $250 in January and said she has given to him in the past because he stands up for issues she cares about. She worked with him on a parkland cause and said in that case he was “a man of courage and principle.”

He asked her for money this election, as have other candidates, Weigum said, but “it wasn’t ever a quid pro quo.”

State legislators are barred from accepting donations from lobbyists during the legislative session, which generally dampens broad-based fundraising solicitations.

“If you do it during [the] session it is a fine line between contributing in order to earn access and contributing in order to earn votes,” Heffelfinger said.

But City Council members are in session all year.

Council Member Jane Prince said working as a council member and running a campaign is complicated. She was a legislative aide for former Council Member Jay Benanav when he ran for mayor. She worked on council issues during the day and fundraisers at night.

“It’s challenging and you have to be super careful,” Prince said. In Thao’s case, “This is a group of people who don’t have a lot of experience,” she said

This is Marlow’s first time managing a campaign, though she previously helped raise funds for a state representative. Thao became a council member in a 2013 special election to fill the spot left open by Melvin Carter, one of his opponents in the mayor’s race. Carter left the City Council to work for Gov. Mark Dayton.

Six candidates are running in the hotly contested race to fill the seat Mayor Chris Coleman is vacating.

Some people have questioned the political timing of the allegations against Thao’s campaign. Fox 9 first aired the text messages between Marlow and Clarke on Saturday evening during St. Paul’s DFL caucuses. Thao came out of the caucuses with the second most delegates, behind Carter and ahead of Pat Harris.

Clarke said she did not want the texts between her and Marlow to get out, and she shared them with someone who leaked them.

Emily Weber, with Carter’s campaign, said they did not send the texts to the press. “It doesn’t help anyone. This sort of thing damages the public trust,” Weber said.