NEW YORK (CNN) -- Two little girls vanished on a warm summer day from a playground near their home on Chicago's South Side. Seven years have gone by since Tionda Bradley, 10, and her sister Diamond, 3, went missing.
This photo shows what Diamond Bradley might look like today. She would be 10.
The girls were left alone at home on July 6, 2001, while their mother, Tracey Bradley, went to work. Bradley last saw her daughters at 6 a.m., as she kissed each goodbye, leaving them to sleep a little while longer.
She returned at 11 a.m. to find the girls gone and a note in Tionda's writing saying they were going to the store and to play at a nearby school. Bradley searched for her daughters frantically that day. By nightfall, she called police for help.
For weeks, police, family, friends and volunteers combed Chicago by foot, air and boat. Dogs were used. Divers searched the ponds and lakes.
Investigators followed up every tip, and at one point desperate family members consulted well-known psychic Gale St. John. But the girls had disappeared without a trace.
Private investigator James Miller volunteered his time and has worked closely with family and police. And just when the Bradleys were losing hope, a break in the case came.
Miller was notified last spring that a young girl's photo on the Internet site MySpace bore a close resemblance to Tionda Bradley. Police followed the lead but came to the conclusion that the girl in MySpace could not be Tionda. Records confirmed the other girl's identity.
"I won't be entirely at peace until they do a DNA test on the girl," said the missing sisters' great-aunt, Sheliah Smith. "In my heart, I believe she could be Tionda."
The massive search for Diamond and Tionda also has led investigators to seek answers in Morocco. One theory is that both girls were kidnapped and taken to North Africa by an Arab man who was angry because he was paying child support for one of the children but found out he was not the father. Watch how Chicago's biggest search turned up nothing »
Authorities have found no signs of the girls anywhere overseas.
Another clue: On the morning the girls disappeared, Tionda left a voicemail on her mother's cell phone about 8:30 a.m., saying "George" was at the door. In the voicemail, she asks her mother's permission to open the door to let him in.
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Tracey Bradley did not get this message until after her daughters were already gone.
Could Tionda and Diamond have opened the door to a stranger who called himself "George" and then snatched them?
It is unclear who he might be. Diamond's father is named George and so is the neighbor who was a part-time baby sitter for the girls. If the girls were taught not to open the door to strangers, neither of these men named George was a stranger.
The police have named no suspects in the case. All family, friends and acquaintances remain "persons of interest," and no one has been ruled out, investigators say.
Today, Tionda would be 17 and Diamond would be 10. Photos of the girls show what they looked like the day they disappeared and what they might look like today through age-progression technology. Police and family urgently ask for the public's help to find Diamond and Tionda Bradley.
There is a $30,000 reward for information that leads to finding the missing sisters. Please call the Chicago Cold Case Unit with tips at 312-746-9690 or use the Web site
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