A white sheriff’s deputy murdered two young men he arrested in unrelated traffic stops almost 15 years ago, according to a wrongful death lawsuit filed in Florida this week. The alleged victims were a black man and a Mexican immigrant, whose bodies have never been found.

Details of the racially charged cold case came to light at a press conference in Naples on Tuesday, at which Tyler Perry, the prominent African American film-maker and activist, offered a $200,000 reward for information resulting in a criminal conviction of the officer.

The civil lawsuit filed on behalf of the victims’ families claims that the two men – Terrance Williams, 27, and Felipe Santos, 24 – were taken away in a squad car by Steven Calkins, a Collier county deputy, in January 2004 and October 2003 respectively but never booked into jail.

Detectives looked into their disappearances at the time, including Calkins’ claims that he dropped both men off at a convenience store after changing his mind. But although he was fired and named as “a person of interest”, he refused to appear before a grand jury, was not charged with a crime and subsequently moved to Iowa, where the lawsuit says he currently lives.

Benjamin Crump, the civil rights attorney representing the family of Terrance Williams, said the legal filing was the culmination of more than a decade of investigative work with the cooperation of the Collier county sheriff’s office, and would compel Calkins to explain his actions in a formal deposition.

“My God, it’s long overdue that he answers questions,” Crump said, standing next to Terrance Williams’ mother, Marcia. “He sleeps every night in his bed peacefully while Marcia and Terrance Williams’ children haven’t had a peaceful night of sleep in the last 14 years, and nor has the Santos family.”

The lawsuit alleges that Calkins was on traffic patrol in January 2004 when he pulled over Williams, who was driving a white Cadillac. Despite not calling in the stop, Calkins drove off with Williams in the back, and later returned alone with the man’s keys to move the car.

In an audio recording of a call the officer then made to dispatch to have the car removed as a traffic hazard, the legal filing says, Calkins “made numerous racial stereotype remarks about what kind of person could own the Cadillac he staged as abandoned”.

Three months’ earlier, the lawsuit says, Santos disappeared “under materially similar facts” after a minor traffic accident in which Calkins arrested him for having no insurance or registration documents. “Santos was never seen alive again after entering Defendant’s patrol vehicle,” the lawsuit states.

Crump said: “The last person to be with them that anybody witnessed was the then Collier county sheriff’s deputy Calkins. These two young men disappeared off the face of the earth and the last man to see them was this deputy.

“His stories were so inconsistent, so unbelievable, and even though he had all these inconsistencies there were no charges brought. This lawsuit is going to formally say what people for the last 14 years have been informally saying, that he intentionally murdered Terrance Williams and Felipe Santos.”

Perry said he believed the case highlighted “a clear disconnect between cultures, between class”.

“When somebody goes missing and they’re a blue-eyed, blonde woman, they’re all over the news,” he said. “This woman [Williams’ mother] has been struggling for so many years just to get attention.

“But no matter who you are, this has got to bother you. If you are decent, human, kind person with a soul, I don’t know how you can’t be upset these two people were put in the back of a sheriff’s car, disappeared, and have not been seen for 14 years.”

Crump added that 680,000 people were reported missing in America in 2014. “What is equally surprising is that 50% were black men, women and children, so it’s a dynamic not known to many Americans,” he said.

The Guardian left a message seeking comment at a telephone number listed for Calkins in Cedar Rapids, Iowa.