Story highlights Fort Lauderdale officers exchanged racially offensive text messages

Three officers were fired, a fourth resigned

Police chief: "There was no criminal behavior detected"

(CNN) Three Florida police officers were fired and a fourth resigned after exchanging a series of racially offensive text messages and a video that portrayed President Barack Obama in a derogatory way, Fort Lauderdale police said.

Jason Holding, James Wells and Christopher Sousa were terminated after a five-month internal affairs investigation found sustained department misconduct, conduct unbecoming of a police officer and engaging in "conduct prejudicial to the good of the order of the police department."

A fourth officer, Alex Alvarez, resigned but authorities said Friday that he would have been fired had he not done so.

In the text message exchanges, the former officers used racially derogatory terms to refer to people they encountered while on duty, included racially insensitive material from the film, "Django Unchained," and talked about getting drunk and "killing n*****," according to investigative documents.

The men allegedly criticized co-workers, including African-Americans, making crude comments about their grammar, appearance and work ethic. One message referred to an entire shift as "lazy f****," the documents state.