Federal prosecutors have filed sex trafficking charges against an Alabama man they say paid more than $20,000 to the father of a Honduran teen in exchange for sex with the boy.

Billy Randolph Edwards, 63, of Huntsville, was initially arrested Sept. 26 by Madison County Sheriff's Office investigators on multiple state charges of human trafficking, sexual abuse and sodomy, according to jail records. Sheriff's Office officials said at the time that Edwards' arrest was part of a joint investigation between its detectives and agents from the Department of Homeland Security.

In an affidavit filed Monday in federal court, a Homeland Security special agent detailed the investigation into Edwards, which began in May. At that time, investigators interviewed the victim in the case, who is now 18.

The young man, who is identified by his initials in the document, told investigators that his father, whose name is being withheld to avoid identifying the teen, smuggled him into the United States in 2014, when the boy was 15. The father and son moved to the Huntsville area.

Shortly after the move, the father began sexually abusing the boy, and forcing him into an ongoing sexual relationship with Edwards for money, the affidavit said. The sexual abuse continued for several months and took place at both Edwards’ home and his place of employment, the federal agent wrote.

Even after the sexual abuse stopped, Edwards continued paying the boy’s father because the father threatened to go to the police, the document said.

The agent wrote that investigators found evidence that corroborates the boy’s claims, including text messages between Edwards and the boy’s father that discuss the abuse.

“For example, on December 23, 2014, Billy Edwards texted (the teen), ‘You want to sell me your (expletive),’” the affidavit read. “Other text messages indicate that (the boy’s father) was aware of the sexual relationship and facilitated it, at least in part by translating text message communications for (his son) when he did not understand a text message from Billy Edwards, and telling (the boy) what to say in response to those text messages.”

Explicit photos, including one of the boy’s genitals, were also found by investigators, the affidavit read.

Bank records also establish a pattern of payments from Edwards to the boy and his father, the agent wrote. Edwards wrote a total of 13 checks to the pair between Nov. 2, 2015, and April 10 of this year totaling about $20,350.

“(The teen) reported that when Billy Edwards paid him (in the form of checks or otherwise), he was typically required to give the money to his father,” the affidavit read.

When local and federal law enforcement officers executed a search warrant at Edwards’ home Sept. 1, they found what appeared to be a handwritten contract requiring Edwards to pay the boy’s father $25,000 for a cellphone that contained data Edwards did not want to fall into the hands of authorities, the court document said.

The affidavit in Edwards’ case, along with a nearly identical document filed against the boy’s father, seeks arrest warrants on the federal charges. It was not immediately clear Wednesday if Edwards had been arrested again, though he is not listed as a current inmate in the Madison County Jail.

WAFF in Huntsville reported that the boy's father is already in federal custody on charges he re-entered the United States after being deported in 2011 and 2012.