TRACY, Calif. -- The United States Coast Guard launched an infrared-equipped C130 airplane Friday night with FBI agents and police onboard looking for clues to Sandra Cantu’s whereabouts.

At 7:00 p.m. Friday, the plane took off and flew over the nightly community vigil held at the mobile home park where the 2nd-grader lives. The plane was also mapping out a preparing for an aerial search Saturday.

“They will take that information, analyze it and determine how they will scope out their search,”” said US Coast Guard Petty Officer Kevin Neff, “

Earlier Friday, a CHP helicopter also equipped with infrared technology conducted a search over farmland and waterways.

Meanwhile, investigators continued their search of the Tracy landfill, looking for any signs of the eight-year-old.

“I’m looking for evidence and I try not to think about anything else,” said Tracy Police officer Ed Gilmore. “When you need to pick through every bag here, it helps to keep you motivated if you just think, ‘I’m looking for a pink shirt,’ or what have you.”

Around 1:30 p.m., about 20 unmarked cars carrying FBI agents and police entered the Orchard Estates mobile home park and served a search warrant on unit number 43. One man who lives in that home left with police and was questioned. Officers told KTVU that other people were questioned Friday as well.

Also Friday, Tracy authorities attempted to deflect criticism that they did not do enough in the early hours of the disappearance of Sandra Cantu.

Police Lieutenant Jeremy Watley told reporters at his morning briefing that authorities decided to deployed their limited resources in a “trailer-to-trailer” search shortly after the girl was reported missing last Friday.

The department has been criticized by some for not immediately putting up roadblocks in the area.

“This was at first just a missing child,” he said. “We were hoping she had just gone off to play with friends, (been) picked up by a family member … We were going from mobile home to mobile home.”

“We only have so many resources… If we could have brought in hundreds of people it (the roadblocks) was something we could have done… Our main focus was just going trailer to trailer to try and find her… Those were the things we were doing.”

“Setting up a roadblock all of sudden … It would have been very manpower intensive… At the same time, she may have been in a mobile home.”

It has been a week since Sandra's family reported her missing from the Orchard Estates Mobile Home Park in Tracy.

The FBI served a search warrant on Thursday at a home in the Central Valley city of Oakdale. The home belongs to a relative of one of Cantu's neighbors, Chris Sinclair. Authorities have already seized three vehicles connected to Sinclair.

Thursday, authorities searched the Old River, which is about 3 miles from her home. Volunteers also sifted through the trash at the Tracy landfill and a second dump site.

"Everything that comes through, they're searching, garbage trucks and everything," said Laurence Campiott, who works at the landfill.

Police also searched the mobile home park again. They previously searched it shortly after Cantu vanished.

Tracy police say a Hello Kitty t-shirt, similar to the one she was last seen wearing, did turn up. Officers showed it to Sandra's mother.

"It looked very similar [to the one she wore], which is why we brought it back to the mother. But mother said it wasn't. That's not to say we're not going further," said Tracy Police Lieutenant Jeremy Watley. "We still have it. It's still going to be examined. It's still going to be tested."

Also on Thursday, police spoke with a neighbor, Frank Wohler, who they say has admitted to once kissing Sandra. Authorities seized Wohler's station wagon Monday night when they searched his home. Investigators returned the vehicle Thursday.

A reward for information leading to Sandra Cantu's whereabouts is growing. It now stands at $22,000.