A man in custody in connection with Kelli O'Laughlin's death sent a text message to the girl's mother, taunting her about what he'd done, a source close to the investigation told NBC Chicago.
This new information has prompted a taskforce of 50 detectives to look at whether this case was indeed a burglary in progress or something more, the source said.
O'Laughlin was stabbed to death last Thursday at her Indian Head Park home after school, police said. Sources said O'Laughlin was stabbed violently, with multiple wounds to the front and back of her body.
Since the crime, officers have followed up on more than 100 leads. One of them panned out, Indian Head Park's chief of police Frank Alonzo said.
"We have a person of interest in custody," Alonzo said. "We are working feverishly to bring this to a close."
Cook County Sheriff Tom Dart has been a frequent visitor to the crime scene and the command center at the Indian Head Police Department. He said he's encouraged by the developments of the last 24 hours.
"It is one of those things where there's a lot of live leads that are -- that we feel positive about -- that we're running out, that I think, should give everyone a certain level of confidence that things are going in the right direction," he said.
According to a source close to the investigation, the suspect, a parolee from Chicago's South Side between 30 and 35 years old, was questioned by an area police agency the night of the murder for an unrelated offense and was released.
NBC Chicago has learned police dogs tracked the suspect's scent from the O'Laughlin home. He took a taxi that evening, a source said, and police are looking for the cab or cab driver to find out whether coins stolen from the O'Laughlin home were used as payment.
The suspect was picked up again Wednesday evening for further questioning. He's not been formally charged.
Still, police understand the sensitivity of the situation as O'Laughlin's visitation continues from 4 to 9 p.m. Thursday in Countryside and her funeral is set for Friday at St. John of the Cross Church, 5005 Wolf Road, in Western Springs.
