SALEM — It was a gruesome cameo in what was an otherwise routine day of jury selection in the trial of a former Marblehead man accused of killing his pregnant girlfriend and unborn baby.

Just moments after 11 prospective jurors were sent home for the day by Essex Superior Court Judge David A. Lowy, a white T-shirt, heavily stained in what appeared to be dried blood, was brought in to the courtroom. Draped over a large piece of flat cardboard and sealed in clear plastic labeled ‘‘Evidence,’’ the T- shirt also appeared to have several inch-long gashes through its middle.