"He said, 'Don't let them get me, don't let them get me,'" Ellis said. "He was totally terrified."
The boy said he had been held captive for nearly a year, said Ellis, adding that he looked as if he were only 10 to 12 years old.
Police arrested Kelly Layne Lau, 30, and Michael Schumacher, 34, late Monday after questioning the couple. A subsequent search of their nearby home found further evidence implicating them, Tracy police spokesman Matt Robinson said.
They were booked on charges of torture, kidnapping and child abuse, and were set to appear in court Thursday, according to online jail records. The couple were being held at San Joaquin County jail on bail of nearly $1.2 million each; county prosecutors did not know if the couple had hired attorneys.
Lau and Schumacher's four young children, two of whom were home when police arrived, have been placed with Child Protective Services, authorities said.
Lau started serving as a local Girl Scout leader sometime in September, after a background check turned up nothing to cause concern, said Pam Saltenberger, chief executive of Girl Scouts Heart of Central California.
According to neighbors, the couple seemed to lead lives that revolved around their kids.
"The victim says he was held against his will," Robinson said. "When you have a 17-year-old boy showing up with a bloody ankle from having a chain wrapped around it, it's one of those things for officers to put one and one together."
On her MySpace Web page, Lau describes herself as a stay-at-home mom and says her husband worked as a contractor. She posted many photos of her family, friends and pets.