SAN ANTONIO -- Teresa Sandoval wants to set the record straight about the disappearance of her 12-year-old daughter Rosa -- her family has nothing to do with it.

In an interview Monday with KSAT 12 News, Sandoval said she is upset with the way police are investigating the case.

Sandoval said police wasted time when they served a search warrant at her home in early July and hauled away the family's car.

"Why do they focus on the family?" Sandoval said through an interpreter. "It really hurts. They have no clues, so they focus on the family."

San Antonio police said evidence technicians found what appeared to be blood stains and bloodied handprints on the walls of Rosa's room, which she shares with 17-year-old sister Gabby. Traces were also found in an adjacent bedroom belonging to her brother.

The search warrant was served at the home after Gabby Sandoval admitted to police that Rosa was actually missing around 11:30 p.m. on May 27 instead of the morning of May 28 when she was walking to school. The missing girl's sister told police the two siblings got into an argument over a glass of tea before the girl left on her own. The new information changed the way the case is being investigated, police said.

Teresa Sandoval, who said she can't eat, sleep or stop thinking about her daughter, said she has faith the 12 year old will appear.

"I don't know where, but she will appear," Sandoval said, "because we won't stand around and do nothing."