(CNN) -- Preliminary FBI lab results show that there were traces of chloroform in the car of the mother of a missing Florida girl, according to a law enforcement source with knowledge of the investigation.
Casey Anthony's computer, confiscated within hours of her arrest in July on charges of child neglect, making false official statements and obstruction of justice, also showed visits to Web sites with information about chloroform.
The discovery of chloroform, a chemical compound that can be used to incapacitate crime victims, is a piece of evidence prosecutors will use in building the case of missing 3-year-old Caylee Anthony.
Earlier, investigators said they had found evidence of human decomposition in the trunk of Casey Anthony's car. Watch a forensic scientist explain chloroform »
Law enforcement sources also suggested that a strand of hair found in the trunk of the car was Caylee's.
Casey Anthony reported Caylee missing in July, a month after the last known sighting of her.
Police jailed Anthony at that time, but a bounty hunter paid the bond that let her out of jail until the charges against her were resolved. Is a dumpster part of the case? »
The bounty hunter said he was going to revoke the bond after threats against his workers, but Casey Anthony was arrested again August 29, this time on charges of forgery, fraudulent use of personal information and petty theft, before he could do so.