The U.S. Department of Justice is investigating whether the civil rights of Robert Ethan Saylor, who had Down syndrome, were violated in a fatal encounter with three off-duty Frederick County deputies who forcibly removed him from a movie theater, Frederick Sheriff Charles A. Jenkins said in an interview Friday.

The investigation comes months after Saylor’s parents and national Down syndrome advocacy groups met with department attorneys to request an independent look into the Jan. 12 death.

Jenkins said he learned of the investigation weeks ago in a letter from the Justice Department and welcomes it. Once investigators review the facts, he said, “they’re going to say: ‘You know what? There is absolutely no excessive force, no inappropriate actions or wrongdoing by these deputies. This is simply an unfortunate situation where this man had a medical emergency while being escorted out of the theater.’ ”

This week, the sheriff’s office released documents detailing its investigation into the death of the 26-year-old. But after reading the 98-page incident report and 22 witness statements, advocacy groups and Saylor’s parents say their concerns about what happened that night have not been allayed.

“We feel strongly, given Monday’s report, that excessive force was used on Ethan and had the situation been handled differently, the three officers could have de-escalated the situation in a number of different ways,” said Sara Weir of the National Down Syndrome Society.

The organization was among those that met with Justice Department officials in February and March. It and the Saylor family have also called on Maryland to launch an independent investigation into the death.

A spokeswoman for the Justice Department’s civil rights division said she could not immediately confirm the investigation.

Jenkins said he expects the Justice Department inquiry to include interviews with the deputies and a review of his department’s internal affairs and death investigations.

“I certainly wish that the Department of Justice would say to the world, ‘They did it right,’ that we did the investigation right,” Jenkins said.

The three deputies — Lt. Scott Jewell, Sgt. Rich Rochford and Deputy 1st Class James Harris — were working off-duty security jobs at the Westview Promenade shopping center when they were called to the theater.

There they found Saylor, who had just watched “Zero Dark Thirty” with his 18-year-old aide and wanted to watch it again. While the aide went to get the car, he slipped back into the theater, and a manager told him that he needed to buy another ticket or leave.

According to witness reports, Saylor cursed at the first deputy who asked him to leave. When the other deputies arrived, the three pulled Ethan, who weighed 294 pounds, from his seat as he wailed and resisted, witnesses said. Several people heard the officers tell Saylor that he was going to jail.

Statements from the deputies were not included in the report, but several accounts in the report said that Saylor lost his balance on a sloped incline and that the officers used it as an opportunity to take him to the ground and handcuff him. When they tried to get him to stand up, they realized that he was unconscious. The officer removed the handcuffs, started chest compressions and called for an ambulance.

The chief medical examiner’s office in Baltimore ruled Saylor’s death a homicide as a result of asphyxia. The report noted that Saylor’s weight, Down syndrome and heart disease made him “more susceptible to sudden death” in situations that compromised his breathing. It also described unexplained damage to his larynx, but none of the witnesses reported seeing the deputies touch his neck.

In March, a Frederick grand jury determined that no charges were warranted against the deputies, who have returned to their full duties.

Saylor’s parents said they hope the Justice Department investigation gives them what they feel they haven’t yet received: an independent, unbiased look at how a young man fascinated with law enforcement officers ended up dead at their hands.

“We’ve just wanted to find out exactly what happened,” Ron Saylor said. “If everybody did everything by the book, as they say they did, things, I’m thinking, would have turned out differently.”

Patti Saylor, who had been driving to the theater that night after getting a call from her son’s aide, said the family is not after criminal charges. They just want the truth.

She believes her son’s civil rights were violated that night.

“I just feel he was devalued,” she said.