Why a house trained dog pees and poops in the house?

i got a free 4 year old german sheppard and collie mix dog today. it is one of the best dogs i seen react to commands. the previous owners said he is house trained and you can leave him alone and he wont bite things, make messes and he doesnt go to the bathroom in the house. this is the first day i had him, i brought him outside right before i left and he went to the bathroom, pee and poop. i left around midnight to pick something up and not even a hour later my landlord called me and said hes crying loud and to please come home, i understand that bc he is new here, but when i got home he peed all over the floor and couch, opened all the doors, got into the garbage can and pooped on my bed. did the previous owners lie to me to get rid of him because he is not housetrained or is it because he is new here. i purposly got a 4 year old because i wanted a dog that was already house trained. if i wanted a dog that made messes and peed and pooped inside i would have got a puppy. someone please help. maybe its just bc hes scared and new to everything here and was alone? i had dogs before and i seen them hold going to the bathroom for a long period of time. he doesnt even drink all his water in the bowl.