He and fellow reporters George Phenix, Wes Wise and Bob Huffaker wrote When the News Went Live about their experiences during that time.
He enjoyed a stint as a sports anchor at KVIL radio station in Dallas-Fort Worth during the 1970s and 80s, alongside longtime morning host Ron Chapman.
[5] On the day of the Assassination of John F. Kennedy (November 22, 1963), Mercer was a news anchor and reporter with Dallas radio station KRLD.
Mercer covered the topic extensively from the field for KRLD and later became the first reporter to inform the assassin, Lee Harvey Oswald, that he would be charged with murder for his actions.
While at KRLD-AM/TV in Dallas, he served seven years as color commentator for CBS Radio's annual broadcasts of the Cotton Bowl Classic college football game.
He also was the announcer in 1959 at UNT when Abner Haynes broke the color line in Texas and later became a star with the second incarnation of the Dallas Texans (American Football League).
Mercer provided play-by-play announcing for the internationally acclaimed World Class Championship Wrestling (WCCW), based in Dallas, from 1982 to 1987.