Published: Aug 28, 2012 8:50 AM EDT

AURORA, Colo. (AP) - Family members of some of the 12 people shot to death during a midnight movie showing in Colorado are speaking out about some behind-the-scenes events they say need to be aired publicly. They have scheduled a news conference for late this morning. A spokeswoman for the group declined to comment on what the families would talk about. A gunman wearing body armor and a gas mask opened fire on July 20 in a packed theater in the Denver suburb of Aurora during a showing of a Batman movie. In addition to the 12 killed, 58 were injured. The 24-year-old suspect, James Eagan Holmes, faces charges of murder and attempted murder. He's being held without bail and hasn't entered a plea. Defense lawyers have said Holmes is mentally ill.