"They left en masse," Jeremiah Donovan said. "It seems to be that is so prejudicial to my client."
Donovan argued the family -- which included William Petit Jr., Jennifer's husband and the father of the two girls -- knew the state's chief medical examiner was going to give graphic testimony Wednesday.
Superior Court Judge Jon C. Blue denied the request, saying spectators are free to come and go from the courtroom, the Hartford (Conn.) Courant reported Thursday.
A medical expert testified Tuesday smoke inhalation killed Hayley and Michaela, and that Hayley -- who was found tied to her bed -- had first-, second- and third-degree burns "all over her body." Hawke-Petit had been raped and strangled.
Prosecutors noted Komisarjevsky admitted he tied both girls to their beds and left them there when the fire started.
Komisarjevsky could face the death penalty if convicted. His accomplice, Steven Hayes, was convicted and sentenced to death in a trial last year.