The Federal Bureau of Investigation said it was looking into whether the victim, identified in the affidavits as Ulises Valladares, who was bound to a chair, was shot by one of its agents as they faced off with an armed abductor in the raid on Thursday in the Houston area.
Nicholas Cunningham, 42, Jimmy Sanchez, 38 and Sophia Heath, 35, have been charged with aggravated kidnapping. The charge can bring up to 99 years in prison.
Montgomery County District Attorney Brett Ligon told a news conference on Thursday that the area's U.S. attorney would "be looking at the possibility of a civil rights case brought against, perhaps, an errant shooter with the FBI."
According to the affidavits, Cunningham and Sanchez went to Valladares' home, used duct tape to bind his hands and the hands of his son, then ransacked the place, took Valladares and left the child behind.
The child freed himself and went to his uncle's nearby home. The uncle, Ernesto Valladares, was contacted by a person who said his brother had been kidnapped by a Mexican drug cartel. The uncle notified the police who, with the FBI, tracked Valladares to the Houston residence where the raid took place.