A second medical expert testified Monday that an existing head injury was most likely the cause of death for a 16-month-old toddler who fell ill at a Lincolnshire day care center in 2009.
Dr. Shaku Teas also said the pathologist who performed the autopsy of Benjamin Kingan of Deerfield failed to diagnose the existing injury and did not follow many of the accepted rules of autopsies.
Teas' testimony came at the start of the third week of the trial of Melissa Calusinski, 25, for first-degree murder in Benjamin's death.
Prosecutors say the Carpentersville woman, who was working as a teacher's aide at the former Minee Subee in the Park day care center, hurled the boy to the floor after she became frustrated with the commotion he and other children were making.
Although Calusinski is shown on video confessing twice that she deliberately threw Benjamin to the floor, the defense argues police took advantage of her low IQ and convinced her to tell them the story they wanted to hear.
Dr. Eupil Choi performed an autopsy the day after Benjamin's Jan. 14, 2009 death and concluded he died of bleeding surrounding a skull fracture the boy suffered within three hours of his death.
Choi told detectives from the Lake County Major Crimes Task Force the fatal injury was inflicted with a force equal to that of a fall from a two-story building.
But Teas said Monday a review of photographs and other documentation from the autopsy convinced her Benjamin had an injury on his brain that was between two or three days and several weeks old at the time of his death.
She said she based her conclusion on cells she detected on slides viewed under a microscope that form around injured areas as they are healing.
It would have been possible for Benjamin to have this type of injury and still appear to be functioning normally, Teas said, because symptoms would not be pronounced enough to cause concern among the adults who observed him regularly.
Teas said it was possible, as the defense has contended throughout the case, that Benjamin aggravated the existing injury through his habit of throwing himself backward while seated and hitting the back of his head on the floor.
Another staff member of the center testified earlier in the trial that Benjamin threw himself backward at Minee Subee at least once on the day he died.
Teas also testified that Choi did not take any photographs during the autopsy that used a tape measure to show the dimensions of the injury, and he failed to collect enough tissue samples from the injured area for examination under a microscope.
Under cross-examination by Assistant State's Attorney Stephen Scheller, Teas said viewing photographs of an injury is a "totally unscientific" way to calculate its age. Other doctors have said the method she used to date the injuries to Benjamin's brain is unreliable.
Teas' testimony was in line with that of Dr. Jann Leestma, a neuropathologist who testified for the defense earlier in the trial and also said he detected a pre-existing injury.
Choi and Dr. Jordan Greenbaum were called by prosecutors earlier in the trial and testified there was no sign of any injury to Benjamin's brain other than the one he suffered on the day of his death.
Both also said it would have been impossible for Benjamin to cause the injury that took his life by banging his own head on the floor.
If convicted of first-degree murder in the case, Calusinski could be sentenced to life in prison.