Police meanwhile were working with an FBI profiler in an effort to get a better idea of who was responsible for the slaying. No arrests have been made.
Cantu's body was found Monday in a suitcase in an irrigation pond north of Tracy. She disappeared from a West Clover Road mobile home park on March 27, setting off an intense hunt that drew national media attention.
Police say the focus of the investigation to find her killer has "narrowed."
Tracy police Sgt. Tony Sheneman said Thursday the hunt for the killer is headed in the right direction and the probe is "not as broad" as when it began. He wouldn't elaborate.
The sergeant says the department has received many tips ranging from, as he put it, "psychic information to information that doesn't make a great deal of sense."
Police have conducted dozens of interviews and served more than 15 search warrants since Sandra disappeared March 27. Her body was found in the suitcase Monday by farmworkers draining an irrigation pond.
"I loved her so much," Maria Chavez said during an emotional interview with Matt Lauer on "Today".
"We don't have any idea who could have done something this horrible to her," added Angie Chavez, Cantu's aunt. "We just are praying that whoever did this gets caught."
Angie Chavez described Cantu as fun-loving and full of energy.
"She loved Hannah Montana," the aunt recalled. "She used to sing 'Best of Both Worlds' all over the house and color and garden. She loved to cook. In fact, the last time that I saw her, she helped me make breakfast."
She recalled how during a trip to Disneyland, Cantu bravely rode the Matterhorn roller coaster.
"At four years old, I thought that was pretty incredible," she added.
Cantu's family members late Wednesday removed stuffed animals and toys from a large shrine that took shape in recent days outside of Orchard Estates Mobile Home Park, where the girl lived with her family. They planned to donate the items to hospitals and organizations that benefit children.
Anyone with information about Cantu's death may contact Tracy police at 209-831-4550. Cantu's family members ask that anyone wishing to make money donations in Cantu's memory contact the Carole Sund/Carrington Foundation or Tracy police Crime Stoppers.