After locating Muerte's room, keep going to the where the bathrooms are located, at the end of the hall. There are two windows covered with dry wall. One of them will crumble if you shoot it. After destroying the dry wall, you can walk outside of the hotel on a small balcony to another "dry wall window". Destroy that, then jump into the room. You will find a plethora of Molotov Cocktails, grenades, and ammo.