Some bruises found on the infant son of a Kings Park man on trial for the child's death may have been "at least several days or a week old," Suffolk County's chief medical examiner said Tuesday.

"Not all the injuries were the same age," Dr. Michael J. Caplan, the medical examiner, said in his second day of testimony.

The father, Christopher Foster, 32, of Kings Park, is on trial before state Supreme Court Justice William Condon in Riverhead, charged with second-degree murder in the death of Jonathan Hertzler, who died when he was 43 days old on Oct. 11, 2011. His injuries included a fractured skull and numerous broken bones. Prosecutors contend Foster never wanted the child and caused the infant's death.

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Defense attorneys counter that the baby's grandmother, who suffers from schizophrenia and lived with the infant's parents at the time, may have somehow caused the baby's death.

"We think the grandmother watching the child injured the baby and Clarissa Hertzler [the mother], her daughter, never said anything about it -- never mentioned it," defense attorney David Besso of Bay Shore said after court. "The baby was acting fussy and congested and was having trouble breathing for a period of time before the baby died, which is very important."

During the trial, Caplan told jurors an autopsy found the infant had 16 external injuries and eight of the 11 injuries found on the infant's scalp appeared to have occurred minutes to a few hours before he died.

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On Monday, Caplan testified that of the 11 scalp bruises he examined two of them showed "signs of healing," meaning the bruises were "one to a few days old."

With respect to the skull fractures found on the sides of the infant's skull, Caplan said two separate episodes may have caused the fractures, but added the fractures could have been caused by a single compression injury, which, for example, could be the compression of the head with both hands at once.

"If it's applied with enough force. It would have to be a very significant force," Caplan testified.

Later in the proceedings, Assistant District Attorney Dana Brown tried to keep a defense witness from testifying. Foster's cousin, Jonathan Foster, was about to start when Brown objected. The attorneys for both sides spoke with the judge in his chambers and then the trial was halted until today, when both sides must argue why or why not the cousin should be allowed on the witness stand.