SALEM, Ore. -- No criminal charges will be filed against Portland Mayor Sam Adams, the Attorney General's office announced after releasing its' report Monday.

"We have done everything we can to determine whether there's sufficient evidence to bring a criminal case," Oregon Attorney General John Kroger said at a noon press conference, "and we have determined that there is not sufficient evidence ... this is the termination of our investigation."

Adams has been under investigation by the state Department of Justice since January, when he came forward and admitted to lying during his mayoral campaign about a relationship with Beau Breedlove, a former legislative intern.

Beau Breedlove (left) and Mayor Sam Adams

Adams denies the two were involved in a sexual relationship before Breedlove was 18 years old.

The mayor said he was relieved by the conclusion and released a statement Monday. More: Adams reacts

"I always felt if it was a fair process and a fair investigation, I would be fine," Adams said. "I was relieved to get it done."

The attorney general conducted a lengthy investigation, interviewing 57 witnesses over a five-month period.

He said the report was finished Monday morning and he had phoned Adams' attorney to notify him before the information was publicly released.

More: DOJ Full Report (PDF)

The DOJ investigation sought to answer five theories of possible wrongdoing, including sexual and official misconduct.

No evidence of underage sex

On the question of whether Adams had sexual contact or intercourse with Breedlove before Breedlove was 18, the report found no evidence to contradict Adams' statements that no underage sex took place. More: No evidence to support 'City Hall kiss'

No evidence of criminal misconduct

The report also found no evidence that Adams hired a Portland Mercury reporter to stop her from pursuing a story about Adams' relationship with Breedlove, which would have constituted official misconduct.

The report also did not find any evidence that Adams used "significant" government resources to disseminate false or misleading information during his tenure as city commissioner or mayor. More: Reporter's connection investigated

No evidence of "theft by deception"
A political candidate who makes false claims during an appeal for campaign contributions may, in some cases, be guilty of "theft by deception." The DOJ report found no references to Breedlove or the rumors surrounding the relationship in any of Adams' campaign fundraising materials, and therefore no basis for criminal charges.

Kroger said although Adams admitted lying to the media, the report did not make any assessment about his credibility. The only way an elected official can be held liable for false statements during an election is in filings with the state. Any statute of limitations on such statements had also run out, Kroger said.

Unsent resignation letter among docs

Kroger's office released dozens of documents Monday, detailing interviews, text messages, emails and other documents from the thorough investigation. One of the most intriguing documents was a transcript of an unsent would-be resignation letter found on Adams' laptop. Read: Unsent letter

Breedlove not 'credible witness'

The report states that the only evidence that Adams may have engaged in illegal sexual contact came from Breedlove. But the report found Breedlove was not a credible witness: "Breedlove's prior inconsistent statements, financial gain, and prior felony conviction for a crime involving deception has compromised his credibility as a witness."

The report concludes: "...there is not sufficient credible evidence to justify criminal prosecution."

Poll: Agree with findings?

Kroger said the case could not rely on testimony from Adams or Breedlove that could not be corroborated. When someone lies to police or investigators, in the state of Oregon, it is not a crime.

"That is just a fact of Oregon law," Kroger said.

Recall effort continues

Adams still faces an organized recall effort that is expected to continue despite the findings of Attorney General Kroger's office.

The group claims he subverted the democratic process with deceptive campaigning and abused his power. It also claims the recall has nothing to do with Adams' sexual orientation.

The group Recall Sam Adams must collect 32,000 signatures, beginning in July, to legally mount a recall effort.

Adams did not say whether or not he felt threatened by the looming recall affort, only that he planned to focus on city business.

The Portland Business Alliance issued a statement saying it was time to move on with city business:

“Clearly, the mayor showed a lack of judgment in having any contact with Breedlove before he turned 18, and it was wrong for him to lie about the relationship when it first became public during his campaign for mayor. However, the attorney general has determined that there is no basis to find that there was illegal contact between the mayor and Mr. Breedlove. For that reason, the attorney general has concluded that criminal charges will not be filed, and there is no evidence to support other charges ... It is time to move on: Mayor Adams must now demonstrate that he can move beyond these personal issues and lead the city at a time when leadership is crucial."

Full coverage: Adams-Breedlove scandal