The boy says his one-time guardian and another man beat him for infractions such as forgetting to water the lawn or not cleaning the bathroom properly. He says they initially hit him with their hands, then escalated to belts, mallets and hammers.
The boy's testimony was made public Friday as part of 970 pages of transcripts from a grand jury hearing in March.
The emaciated boy was 16 when he escaped the house in Tracy in December and stumbled into a nearby fitness center, nearly naked.
Four people have pleaded not guilty to torture and other charges.