TRACY, Calif. -- The search for a missing 8-year-old girl has expanded to a home in Oakdale and a search of a Tracy waste facility, authorities said Thursday.

Volunteers and police were searching the trash facility – located about seven miles from the mobile home park where Sandra Cantu disappeared last week -- and also the refuse from “every Tracy resident” before it is taken to the dump, said Tracy Police Lt. Jeremy Watney.

At his morning news conference, Watney also confirmed a home in Oakdale had been searched but could not release any other details. In all, Watney said, four mobile homes have been searched at the park, another location in Tracy and the home in Oakdale.

Authorities also were continuing their sweep of the nearby San Joaquin Delta waters by a sheriff’s department boat.

Among the other discloses from Watney’s news conference was that polygraphs had been given to some individuals in the case, but he refused to release those names, that every lead from “video tapes to psychics” were being followed up on and that there have been no searches conducted in Mexicali, where Cantu’s father lives.

On Wednesday, Cantu’s father sent a message to his daughter to "scream, kick, do what you need to do."

Cantu's father Daniel told reporters he met with police extensively.

"I've just gotten through a couple hours of being interrogated," he said.

Cantu is divorced from the Sandra's mother and says he lives in Mexicali on the Mexican border. He said he hasn't seen Sandra in a year. He also said police asked him if he had taken his daughter to Mexico and he said no.

Cantu had a message for his daughter: "Honey, if you can get to a phone, dial 911 babe. Scream. Kick. Do what you need to do."

Police said Wednesday that they're sorting through more than 500 leads in their search for Cantu.

The missing girl's family is urging the community to continue its support and prayers and the community did just that Wednesday night, holding another vigil at the mobile home park.

One speaker was a Vallejo girl who survived a kidnapping in 2000 when she was eight-years-old. She managed to escape from her abductor.

Midsi Sanchez told the group, "Look at me. You have to have to hope."

At the Tracy landfill, volunteers supervised by police sifted through garbage in search of clues. Police said they are looking at all possibilities.

"We're not ruling anything out, because the moment we do is when we're proven wrong. So we're leaving it all open," Watney said. "We're going to treat it as as missing person, as a runaway, possibly foul play."

So far, law enforcement has towed away four vehicles from the mobile home park. Police have been scanning video from three surveillance cameras at the Microtel Inn that are focused on the front entrance to the mobile home park.

"They could focus in on one of the cars beyond what we can see. They might catch a break," explained motel manager Juan Rentan.