In the final draft script of "Silent Enemy", Mark Latrelle is described as being in his "late 20's." The character was played by John Rosenfeld.
Latrelle was scripted to be wearing "a different mission patch on his shoulder" than the equivalent patch for Enterprise. The assignment patch worn by Latrelle was, in reality, a NASA Mission Control emblem. It was provided by William Foster, a ground control officer at the Johnson Space Center. (Star Trek Encyclopedia (4th ed., vol. 1, p. 456)) It was not revealed which starship or facility this emblem belonged to and it was never seen again.