Marco Lopez joined the Houston Police Department in 2001. He was assigned to Patrol from 2001-2004, the Northeast Divisional Tactical Unit from 2004-2007, and Special Investigative Narcotics Division from 2007-2010. He started as a part time member of HPD SWAT in 2007 and became a full-time entry team member of SWAT in 2010. In 2013, Marco Lopez became an Assault Team Leader, holding that billet until he was promoted in 2019, Sergeant Lopez returned to HPD SWAT as a full time SWAT supervisor.