Special counsel Robert Mueller's investigation did not conclude whether President Donald Trump obstructed justice after looking into numerous potential instances, in part because of issues in determining the president's intent. In a more than 400-page report summarizing the probe into Russian efforts to interfere in the 2016 election released Thursday, Mueller's team outlined why it "does not conclude that the president committed a crime" but also "does not exonerate him." The document states that the evidence obtained about Trump's "actions and intent presents difficult issues that prevent us from conclusively determining that no criminal conduct occurred." In the absence of a conclusion by Mueller, the Justice Department determined that Trump did not obstruct justice. In explaining the decision, Attorney General William Barr said he and Deputy Attorney General Rod Rosenstein considered not only whether the acts were "obstructive" but also the president's intent in taking those steps. Barr in part cited "substantial evidence" in Mueller's report "to show that the president was frustrated and angered by a sincere belief" that the probe undermined his presidency.

Robert Mueller Getty Images

The Mueller report cites three problems with drawing a conclusion on obstruction: the president's constitutional authority, the lack of sufficient evidence that Trump committed a crime related to Russian election interference that he would want to cover up and the fact that some of his actions took place in public view. Trump's lawyers argue the president cannot commit obstruction, though Mueller's team suggested it does not agree. The special counsel's team notes that it thinks Congress has the authority to investigate the president for obstruction. It "concluded that Congress has the authority to prohibit a President's corrupt use of his authority in order to protect the integrity of the administration of justice," Mueller's office writes. Mueller's team looked into several critical events to determine whether Trump obstructed justice: His actions related to the FBI investigation into former national security advisor Michael Flynn, including the president asking former FBI Director James Comey to "let [the probe] go"

How Trump reacted to Comey publicly confirming the Russia investigation and the president's efforts to get ex-Attorney General Jeff Sessions not to recuse himself from it

The president's decision to fire Comey and the White House's explanation of the move

Trump directing former White House counsel Don McGahn to remove Mueller, which McGahn ultimately did not do

The president aiming to limit the investigation only to future election interference and his subsequent criticism of Sessions

Trump's efforts to prevent the disclosure of information about a 2016 meeting in Trump Tower between campaign officials and Russians

The president's push to get Sessions to undo his recusal from the investigation

Trump's actions toward Flynn, his former campaign chairman Paul Manafort and ex-personal attorney Michael Cohen as they faced legal scrutiny Mueller's team writes that its investigation "found multiple acts by the President that were capable of exerting undue influence over law enforcement investigations, including the Russian-interference and obstruction investigations." It says his "efforts to influence the investigation were mostly unsuccessful, but that is largely because the persons who surrounded the President declined to carry out orders or accede to his requests."