A Chicago man pleaded guilty Monday to an attempted bombing near Wrigley Field.

Sami Samir Hassoun admitted that in September of 2010, he placed a backpack with what he thought was a bomb inside a trash can by Wrigley Field. Undercover FBI agents gave him that backpack after meeting with him multiple times during the summer to plot the attack.

FBI agents also have videotape of the 24-year-old at places around Wrigley where he said an attack could have minimal risk but maximum impact. Federal prosecutors said that the undercover agents gave Hassoun many chances to bow out of the plan, but he continued to reassure them he wanted to be involved.

Hassoun spoke very little at the hearing, only saying, “yes, your honor,” or “no, your honor,”  when prompted. He pleaded guilty to two counts: attempted use of a weapon of mass destruction, and attempted use of an explosive device. Hassoun was arrested in 2010 and remains in federal custody.

The maximum recommended sentence is life in prison and up to $500,000 in fines. Under the plea agreement between Hassoun’s lawyers and the government, Hassoun could serve 20 to 30 years in prison. He had originally pleaded not guilty.

Judge Robert Gettleman called the case “very serious” and set a sentencing date for this August.