One of the biggest questions still looming over the Oct. 1 Las Vegas shooting is how Stephen Paddock was able to pull off the massacre without triggering any suspicion from hotel staff. Mandalay Bay Resort and Casino has been accused of failing to check the gunman’s room in the three days leading up to the shooting. The hotel’s parent company, MGM Resorts International, insists the Mandalay staff had more than 10 interactions with Paddock during his stay and did not notice anything weird or alarming.

“Mandalay Bay staff, room service and housekeeping had contact with Paddock or entered his suite more than 10 times over the course of his stay, including the three days leading up to October 1,” an MGM Resorts spokesperson told The Las Vegas Review-Journal via e-mail. “There were numerous interactions with Stephen Paddock every day at the resort, including a room service delivery and a call with housekeeping on October 1, all of which were normal in nature.”

Because details of the interactions have not yet been revealed, it is unknown if any staff members ever entered the gunman’s room, where he kept an arsenal of weapons.

Paddock broke the window to his room on the 32nd floor and fired more than 1,100 rounds of ammunition into a nearby open-air country music festival. 58 people were killed in the shooting, and hundreds were left injured. The 64-year-old fatally shot himself right before law enforcement made their way into his room.

The motive behind the massacre remains a mystery to this day.