He co-wrote the teleplay for the episode "Vanity" with Ray De Laurentis and John Tinker from a story by producer Tom Fontana.
He returned as a writer for the third season and co-wrote the teleplay for the episode "Saving Face" with Norma Safford Vela from a story by Fontana.
He wrote the teleplay for the episodes "A Shot in the Dark" and "And the Rockets' Dead Glare", both were based on stories by Fontana.
Noel Behn wrote the teleplay for the episode "A Model Citizen" from a story from Zamacona and Fontana.
Randall Anderson wrote the teleplay for the episode "The Old and the Dead" from a story by Zamacona and co-executive producer Henry Bromell.
Chernuchin and Zamacona also collaborated on the sixth season Law & Order episode "Charm City" in 1996.
In 1996, Zamacona was hired as a co-executive producer and writer for new Fox Network science fiction series Millennium.
In 1999, Zamacona served as an executive producer and writer for CBS pilot St. Michael's Crossing but the network did not order a series.
Zamacona joined the crew of TNT occult police drama Witchblade as a consulting producer and writer in summer 2002.
In fall 2002, Zamacona was hired as a writer for the third season of NBC emergency services drama Third Watch.
The series was created by retired Chicago police officer Edward Allen Bernero and television producer John Wells.
The series focused on police officer, firefighters and paramedics working the same shift as one another in New York City.
Zamacona co-wrote the episode "The Unforgiven" with producer Scott A. Williams and executive story editor Julie Hébert.
In 2003, Zamacona reunited with his Homicide colleague Tom Fontana as a supervising producer on the sixth and final season of HBO prison drama Oz.
In fall 2003, Zamacona co-created the ABC police drama 10-8: Officers on Duty with Louis St.
Co-executive producer Frank Renzulli wrote the teleplay for the episode "Gun of a Son" from a story by Zamacona and St. Clair.
Bradford Winters wrote the teleplay for the episode "Flirtin' with Disaster" from a story by Zamacona and St. Clair.
[8] The next year, Zamacona stayed with TNT as the Co-Executive Producer and Writer on The Last Ship that starred Eric Dane.
In 2019, Zamacona resumed working alongside Tom Fontana for Showtime's City on a Hill , starring Kevin Bacon and Aldis Hodge, as a Co-Executive Producer and writer.