(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. Alvarez created a faux movie trailer with the title "The Hoods," with offensive language and images of Obama, the Ku Klux Klan and African-Americans. "There was no criminal behavior detected during this investigation, however, the four officers' conduct was inexcusable and there is zero tolerance for this kind of behavior in the Fort Lauderdale Police Department," Chief Franklin Adderley told reporters. "Its attempt was to damage the image of our agency and I just hope that the people and the public realize that we're not going to tolerate it and anyone that's engaged in this behavior will be addressed immediately," he said. In a statement, the Fort Lauderdale Fraternal Order of Police said the officers deserve their due process, CNN affiliate WSVN reported. "The Fraternal Order of Police is a multicultural organization which does not tolerate racism," the group's president, Jack Lokeinsky, said in the statement. "Our officers take great pride in our commitment to diversity. Our dedicated officers have positive relationships with residents in every community we serve." The officers worked in a predominantly African-American neighborhood. "I am very disappointed, disgusted and shocked by this incident," Mayor Jack Seiler said. "The inappropriate racist behavior exhibited by those involved is unacceptable and reprehensible, it violates the trust we place in our law enforcement officers, it damages the bond we have established in our community and undermines the standards in which each and every city employee is held accountable," Seiler said at a news conference. Police officials were alerted of the existence of offensive material by Alvarez's ex-fiancee, who discovered it when the couple agreed to check each others' phones, according to the documents. The woman told police she thought their behavior was wrong, but feared he would hurt her if she told anyone. After the 10-month relationship ended, she went to the authorities. Adderley said that four officers had not exhibited a pattern of race-related complaints. Holding was recently disciplined with a two-day suspension for mishandling property of a suspect. The police department is implementing a mandatory "diversity class" for officers and a screening process for new hires,  said Adderley.
Fort Lauderdale officers exchanged racially offensive text messages . Three officers were fired, a fourth resigned . Police chief: "There was no criminal behavior detected"