An Ohio man has pleaded guilty to plotting to attack the U.S. Capitol with guns and bombs and faces up to 30 years in prison

Christopher Cornell, 22, dressed in black-and-white striped jail clothes and shackled, pleaded guilty in U.S. District Court in Cincinnati to attempted murder of government officials, possession of a firearm to commit a crime and attempting to provide material support to the Islamic State militant group.

A fourth charge of solicitation to commit a violent crime will be dismissed at his sentencing on Oct. 31, said one of his attorneys, Eric Eckes. Cornell, who mainly answered the judge's questions with "yes ma'am" and "no ma'am" responses, faces five years to 30 years in prison.

Another Cornell attorney, Martin Pinales, said after the hearing that the guilty plea was in the best interest of his client.

Cornell, of Green Township, Ohio, near Cincinnati was arrested in January 2015 and accused of plotting an attack using pipe bombs and bullets. He initially pleaded not guilty.

In April, U.S. District Judge Sandra Beckwith in Cincinnati ruled that Cornell, who has been held without bond since his arrest, was competent to stand trial. Last November, the judge ordered a psychiatric evaluation for Cornell after his attorneys questioned his mental competence.

Cornell researched the construction of pipe bombs, purchased a semi-automatic rifle and 600 rounds of ammunition, and made plans to travel to Washington to carry out the plot, according to the original indictment.