Scott, who was chosen at the city's Police Chief in 2010, took an abrupt leave of absence nearly three weeks ago. His resignation will be effective May 1.
"I am a law enforcement officer, but I forgot that I also have a family," said Scott.
Scott reflected on a young man, Richland County Deputy Byron Keith Cannon. Cannon, 24, died on May 4, 2005 after being hired by Scott. A bill from the 116th session of the South Carolina General Assembly states Cannon died "while responding to a call of someone who needed his protection." The Associated Press reports Cannon was following a dump truck when he lost control of his cruiser on Interstate 20 in Lexington County.
"That was something I couldn't let go," said Scott.
Scott previously served as a Richland County deputy. He said he realized recently during counseling that he was still affected by Cannon's death. He says he was telling his story to enlighten the community on the stresses law enforcement go through.
"They call it PTSD, they call it stress, but I have to call it what it is, and it's something that was tearing me apart for a very long time," said Scott.
Scott thanked City officials and the Columbia Police Department for their support.
"It would be selfish of me if I did not share this with the community and the law enforcement community," said Scott.
Scott was not taking any questions from media.
Mayor Steve Benjamin said Scott has "served his country and community well."
City Manager Teresa Wilson says the search for a new police chief will begin when the time is appropriate.
Deputy Chief Ruben Santiago has served as Acting Chief of Police during Scott's leave. He will become Interim Police Chief in May.
"Our goal in public safety is to make sure we keep our citizens safe," said Santiago. He says he is "grateful for the leadership and friendship from Chief Randy Scott."
In January, Scott was sworn in as police chief for the second time after retiring and reapplying for the position due to changes of the state police retirement system.
At that time, Scott said he was looking ahead to this year with youth intervention and prevention high on his list of priorities.
A City of Columbia spokesperson confirmed in January that under Chief Scottâ??s tenure, he helped to establish a PACE Team, Drug Suppression Team and also reduced overtime by 72 percent.
According to the CPD website, the department has had 10 chiefs in the past 13 years. They are as follows:
1990 â?? 2001 â?? Charles Austin Sr.
2001 â?? 2002 â?? Charles Clark (Acting Chief)
2002 â?? 2004 â?? James Swisher (Acting Chief)
2004 â?? 2007 â?? Dean Crisp
2007 â?? 2007 â?? Harold Reeves (Interim Chief)
2007 â?? 2008 â?? Norman Caldwell (Interim Chief)
2008 â?? 2010 â?? Tandy Carter
2010 â?? 2010 â?? Carl Burke (Interim Chief)
2010 â?? 2013 â?? Randy Scott
2013 â?? ? â?? Ruben Santiago (Interim Chief - effective May 1)
(The Associated Press contributed to this report.)