Mark Day was a Westec Security guard who responded to a 1985 disturbance call at the Rockingham estate, where he witnessed the aftermath of a domestic violence incident involving Nicole Simpson — years before it became central to the case. By the time he testified, Day had become an LAPD sergeant, and the defense seized on the nine-year gap between the incident and his 1994 statement, as well as his prior conversations with Detective Fuhrman, to challenge the reliability of his recollections. The defense further highlighted contradictions between Day's and Fuhrman's accounts of damage to a Mercedes at the scene, casting doubt on the consistency of the prosecution's domestic violence narrative.