Police searched the homes and towed the vehicles of two men Monday who live in the same mobile home park as a missing 8-year-old girl.
Both men live in the Orchard Estates Mobile Home Park, where Sandra Cantu also lives and was last seen Friday.
A Tracy police spokesman says officers are investigating the men they say are "persons of interest" in the case.
Items collected in the searches were turned over to the FBI crime lab for analysis.
Police are not saying why the two men have attracted the attention of investigators. The names of the men have not been released.
Meanwhile, the reward for information has grown to $7,000. Investigators are tracking down more than 150 tips that have come in from the public.
Police say there is no evidence Sandra was abducted or the victim of foul play. But the girl's mother told the "Today" show that she fears her daughter was abducted.
Sandra was last seen on surveillance video Friday afternoon in the mobile home park where her family lives.