Price, Utah (AP) Federal mining regulators are briefing family members on an investigation into the fatal cave-ins at Utah's Crandall Canyon mine that killed nine people last summer.

The Mine Safety And Health Administration planned an hours-long Powerpoint presentation for dozens of people, including lawyers and a union representative.

Two police officers guarded the door to a conference room at a hotel in price, about 20 miles east of the mine.

The Aug. 6 collapse was so powerful that it registered as a 3.9 earthquake at the university of Utah. Trapped deep inside were six miners whose bodies have never been recovered. Three others were killed as rescuers tried to tunnel toward the trapped miners.

MSHA chief Richard Stickler said before opening the briefing that the sights and sounds of the disaster will stay with him forever.