Three of the four people accused of torturing and shackling a teenage boy in a Northern California home for more than a year pleaded not guilty.

The pleas by homeowner Kelly Layne Lau, the boy's one-time guardian Caren Ramirez and next-door neighbor Anthony Waiters came after a San Joaquin County judge unsealed the grand jury indictment against them Wednesday.

The fourth defendant, Lau's husband Michael Schumacher, hasn't entered a plea. He's expected to do so at the next court hearing April 28.

Authorities say the 16-year-old victim escaped from the home in Tracy by unlocking an ankle chain and stumbling into a health club in December.

Charges against the four include aggravated mayhem, torture and false imprisonment.