(CNN) -- A Florida judge ruled Wednesday that the jury in the upcoming trial of Casey Anthony can hear testimony that chloroform, a potentially fatal substance, was detected in the trunk of the woman's car.
Prosecutors contend that Anthony used "a substance" to kill her 2-year-old daughter, Caylee.
Anthony, 25, faces a capital murder charge in the death of her young daughter, plus six other charges including aggravated child abuse, aggravated manslaughter of a child and misleading law enforcement. The girl was reported missing in July 2008, about a month after she was last seen. It wasn't until five months later that investigators found her remains.
Orange County Superior Court Chief Judge Belvin Perry Jr. wrote that Arpad Vass, a research scientist at Oak Ridge National Laboratory, will be allowed to testify about whether and how chloroform was found in Anthony's car.
Perry said testimony on chloroform will be admissible as long as prosecutors can establish a proper foundation for it.
His decision is a setback for the defense, which comes just one day after he sided with prosecutors on three other key evidence rulings.
First, Perry ruled that "heart sticker" evidence will be admissible as long as prosecutors can establish a proper foundation. A FBI fingerprint examiner has testified that she saw residue consistent with the shape of a heart on duct tape found near Caylee's remains.
Heart-shaped stickers were found at Anthony's house.
Second, Perry ruled Tuesday that expert testimony about post-mortem hair banding will be admissible. Prosecutors say evidence of decomposition was found on a single strand of hair taken from the trunk of Anthony's car -- where, prosecutors allege, she stashed her daughter. Post-mortem hair banding is said to occur when the hair begins to decompose inside the hair follicle while still on the head of the deceased.
Finally, he ruled that canine searches and alerts will be admissible at the trial as long as the state establishes a proper foundation. Cadaver dogs searching for Caylee's body signaled at two places -- the trunk of Anthony's car and in the backyard of her parents. Remains were not found at either location.
Anthony's case has generated an intense media spotlight because of its shocking nature -- prompting the court to move jury selection, scheduled to start on May 9, to another location because of concerns about getting an impartial jury in Orange County. Jurors will be transported to Orange Country for the trial.
In Session's Nancy Leung contributed to this report.