(AP) — A woman and her boyfriend have pleaded guilty to abusing her 15-year-old son, who was kept inside their home in Michigan’s Upper Peninsula for four years.

The guilty pleas came Thursday after the couple waived their right to a key hearing to determine whether there was enough evidence for trial.

Police say the boy rarely left a room made from tarps while being tortured and abused. He was rescued from the Escanaba home in April.

His 46-year-old mother pleaded guilty to first-degree child abuse and torture. Her 47-year-old boyfriend pleaded guilty to first-degree child abuse and no contest to aiding and abetting first-degree criminal sexual conduct.

Sentencing is scheduled for August. They could face up to life in prison.

Their names are being withheld to protect the boy’s identity.