Who saw Dexter placing the bodies in his car? ("Dexter" S:01 E:05)?

In season 1 episode 5 of the Showtime Original Series "Dexter", immediately after killing the two Cuban traffickers, Dexter Morgan is shown placing the wrapped bodies in the trunk of his car. As he walks to the drivers door to leave the camera cuts to a frame that shows the trunk of a car nearby in the junkyard. Through the keyhole in the trunk there is a human eye watching Dexter. Who is it that sees Dexter? Is it the ice truck killer?