SAN DIEGO -- The search for Jahi Turner expanded beyond the area around the Balboa Park playground from which the toddler vanished as police combed through trash at the Miramar landfill for clues in the case.

MISSING JAHI TURNER Light-skinned African-American 30 pounds, 30 inches tall Black hair Wearing blue "Winnie the Pooh" T-shirt, blue pants, and gray tennis shoes INFORMATION Citizen Access Phone System: (619) 570-1070 Tip Hotline: (619) 235-8477 Download A Missing Flyer SOUND OFF Share Your Thoughts

Authorities would not say what prompted them to begin the daunting task of sifting through tons of refuse in search of evidence, other than to report it was not a tip that led investigators there Tuesday.

San Diego Police and crews from San Diego City Environmental Services set up a command post at the landfill.

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Police: We Have Not Found Anything Details On Landfill Investigation

"The bulk of our activity ... has been at the Miramar landfill, where we have detectives searching for any clues, anything at all, that might tie to this case," San Diego police information officer Dave Cohen said late Tuesday afternoon.

"I'm not going to discuss where we're looking in the landfill or why we might be looking in that particular location," Cohen said.

Investigators will "stay out there around the clock, if needed, before we leave there -- to be sure that we have covered everything that we possibly can at that location," Cohen added.

Earlier Tuesday, avoiding reporters' shouts of "Why did you leave your baby for 15 minutes?" the stepfather and mother of Jahi ended a short news conference at a South Park search center.

It was the first time the public had heard from Tieray Jones, 23, who last saw his stepson Thursday, April 25, when he stepped away from the boy and walked a few hundred yards to get a soda at a vending machine.

When Jones returned about 15 minutes later, his stepson was gone.

"Me and my wife have learned that there are many children that are missing from the San Diego and California area ... No child should go unsearched for, or missing, or just put in some file," Jones said at the conference outside the volunteer search center, stopping abruptly to choke back emotion.

Tameka Jones, 18, had appeared earlier in the morning on ABC's "Good Morning America" program, alongside Brenda van Dam. Van Dam is the mother of Danielle van Dam, the slain 7-year-old who was abducted from her Sabre Springs home two months ago.

As she had earlier in the morning, Tameka Jones issued a plea for her son's safe return.

"We just want to tell whoever the person that has our son: If you could just drop him off at a safe place, so that someone that's caring can bring him home to us," the child's mother said. "We don't care who this person is, we just want Jahi back."

Tameka Jones described her son as "a really sweet child" who "loves Winnie the Pooh."

Van Dam said she was offering Jones emotional support and said she had urged her to "come in front of the camera and to ask for help and to ask whoever has her baby to let him go."

Van Dam also said her advice to Jones was to "be strong and to never give up hope."

Jahi's stepfather told authorities he left the boy with a woman and two other youngsters at a play area near in a corner of Balboa Park, near 28th and Beech streets.

The park is considered a generally safe area, though it is bordered by busy streets, and nearby canyons are used as campsites by homeless people.

"It's a perfectly safe park in a perfectly safe community," resident Suzanne Torrence said as she played with her 3-year-old son, Gabriel, in the play area where Jahi disappeared. "But you just don't leave your kids alone for 15 minutes, even in Beverly Hills."

Authorities announced Monday that they had tracked down the woman who Jahi's stepfather said was in the park minutes before the toddler disappeared.

"We have spoken with her and will be speaking with her again," Cohen said. "We will not discuss how we located her or what she may have told us."

The potential witness, who authorities declined to identify, was not considered a suspect in Jahi's presumed kidnapping, he added.

"We have no suspects whatsoever," Cohen said.

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Parents Issue Short Statement Hear From Mother, Brenda van Dam

Tameka Jones (pictured, left), who is in the Navy, had been away for a week of maneuvers aboard the dock-landing ship USS Rushmore and was returned to San Diego shortly after her son's disappearance.

The child had been living with his grandmother in Maryland until earlier this month, when his mother moved with him to San Diego.

Many of the same volunteers who looked for Danielle have been searching for the toddler in canyons and neighborhoods around the downtown park.

"I just hope it's not going to end the way it did with Danielle," van Dam said.

Jahi is a light-skinned African-American, about 30 inches tall and weighing 30 pounds. At the time of his disappearance, he was wearing a blue, long-sleeve T-shirt with a rendering of the "Winnie the Pooh" cartoon character on it, blue nylon pants with an orange drawstring and gray "Michael Jordan" tennis shoes.

Officials urged anyone with information in the case to call San Diego County Crime Stoppers' anonymous tip line at (619) 235-8477 or SDPD communications at (619) 531-2000.