The 35-year-old man, whom police refused to identify, was arrested for alleged illegal detention, abuse, issuing severe threats and injuries against his mother and sister, who is physically disabled, in the southern city of Seville, they said in a statement.
He reportedly would let the victims out occasionally, and during one of the “leaves” they went to the police and reported him, despite regular death threats he made against them backed by a gun and a machete.
The suspect reportedly tied them up with ropes and only allowed them to relieve themselves with his permission.
Police said the victims were not allowed to eat when he was in the home.
“Once he stayed at home for three days and therefore the victims did not eat for three days,” they said.
To prevent the victims from escaping, their rooms had doors that could be locked from the outside.
“When they searched the home, agents found that both victims shared these two bedrooms with dogs that relieved themselves in there as did the women, who did it in buckets as they were not allowed to use the bathroom,” police said.
It is unclear when the ordeal started, but police said the mother had lost 20 kilos (44 pounds) in the past few months, and was in a “terrible personal and hygienic state.”
The case echoes that of an American couple who held their 13 children captive in their home, some shackled to beds in foul-smelling surroundings, in a case that shocked the United States.
And in 2015, a similar case hit southern Spain near Seville.
Police detained a man and a woman who kept their 59-year-old brother locked up naked in a tiny, roofless room adjoining their home, on a filthy mattress next to which bottles and buckets were laid out for him to urinate into.