Prosecutors have started to make their case against the man charged with carrying out a deadly rampage at a U.S. movie theater in July.

The preliminary hearing in the case against 25-year-old James Holmes got underway Monday in Colorado.

Prosecutors have filed more than 160 counts against James Holmes for the shooting attack that killed 12 people and wounded 58 others. Before the hearing began, people began lining up outside the courthouse, including relatives of the victims.

The hearing is expected to last a week, with prosecutors publicly outlining their case against Holmes for the first time. A judge will then decide whether to proceed to trial.

Prosecutors have not yet determined if they will seek the death penalty.

Authorities say Holmes attacked the theater during a midnight screening of the Batman film The Dark Knight Rises, throwing tear gas canisters inside before opening fire on the audience.

Holmes was a Ph.D. student in neuroscience, but withdrew from his program a month before the shootings.

His lawyers have said he is mentally ill, and court records indicate they may call witnesses at the preliminary hearing to testify about his mental state.