A House of Representatives panel investigating last year's deadly Capitol riot on Monday called on the Justice Department to bring criminal charges against former President Donald Trump for his efforts to overturn his loss in the 2020 presidential election.

The development wrapped up a year-and-a-half probe by the Democratic-led select committee into the Jan. 6 attack on the Capitol by a pro-Trump mob. The panel's request is not legally binding, but could add pressure on authorities to move forward with prosecution.

A mob loyal to U.S. President Donald Trump gathers near the U.S. Capitol in Washington on Jan. 6, 2021. The move came after Trump urged his supporters to descend on Washington to protest Congress' impending certification of Joe Biden as the winner of the November presidential election. (Kyodo) ==Kyodo

In a summary outlining the findings of the investigation, the committee said its hearings presented evidence that led to "an overriding and straight-forward conclusion."

"The central cause of January 6th was one man, former President Donald Trump, who many others followed. None of the events of January 6th would have happened without him," the document said.

Trump has been criminally referred by the committee for four charges -- obstruction of an official proceeding of Congress, conspiracy to defraud the United States, conspiracy to make a false statement, and inciting or assisting an insurrection.

The former Republican president has been accused of responding to his 2020 election loss by summoning his supporters to Washington on Jan. 6, 2021, and sending them, including some who were armed, to the Capitol while Congress was engaged in a process to certify Democrat Joe Biden's election win.

During a rally in Washington earlier that day, Trump told his supporters to march on the Capitol and "fight like hell" or "you're not going to have a country anymore."

Trump has also been criticized for his failure to act in a timely manner to stop the violence or protect Congress after a pro-Trump mob swarmed the Capitol, resulting in lawmakers pausing the certification process to take shelter.

The House impeached Trump in the final days of his presidency over his role in the Capitol attack. He was later acquitted in a trial in the evenly divided Senate.

Following this year's Nov. 8 midterm elections, the 76-year-old announced his bid for re-election to the presidency in 2024, although his influence seems to be waning after many of his favored candidates fell short in the polls that decided control of Congress from January.