The U.S. Department of Justice is reviewing the actions of Dallas police officers in the 2016 death of a man who called 911 for help, a spokeswoman for the district attorney's office told The Dallas Morning News.

The mystery surrounding Tony Timpa's death was the subject of an investigation published by The News in September 2017.

Three officers were indicted last year on misdemeanor charges in Timpa’s death, which occurred two years ago. Officers were accused of restraining Timpa in a way that led to his death.

Tony Timpa

The Dallas County DA’s office declined to comment on why the case has not yet been prosecuted.

"DOJ is reviewing this so with it being a pending investigation I won't be able to get answers to your questions at this time," Kimberlee Leach, a spokeswoman for the DA's office, told The News via email Thursday:

A spokeswoman for the Department of Justice declined to comment.

Timpa, 32, died -- unarmed, handcuffed and frightened -- in the custody of Dallas police officers on Aug. 10, 2016.

A private security guard handcuffed Timpa before Dallas officers arrived; he was unarmed, in shorts and barefoot, near the parking lot of a porn store.

The medical examiner ruled that his death was a homicide. The cause was sudden cardiac death, due to the toxic effects of cocaine and the stress associated with physical restraint.

A few months after The News published its investigation, three of the officers involved in his death -- Sgt. Kevin Mansell and officers Danny Vasquez and Dustin Dillard -- were indicted on misdemeanor deadly conduct charges.

The officers were placed on administrative leave after the indictment. Dallas police did not immediately respond to questions about whether the officers remain on leave.

Mansell is a 27-year veteran of the Dallas Police Department. He was previously suspended for one day for his role in handling a 911 call about D'Lisa Kelley, who was later found dead. Mansell was also involved in an off-duty shooting of two teenagers as a rookie.

Tony Timpa died in August 2016 after he ran out of the New Fine Arts store on West Mockingbird Lane, panicked and afraid. He called 911. Private security guards working in the area handcuffed him, then Dallas police arrived. He was dead in less than an hour. (Andy Jacobsohn / Staff Photographer)

Dillard was hired by the Dallas Police Department in March 2015, and Vasquez had served on the force for at least four years.

Immediately after the charges were announced, the officers' union criticized them as "baseless."

Attorneys for the officers have argued in court filings that Timpa “violently kicked and rolled while he was perilously close to the roadway.”

The News began requesting body camera footage, incident reports and a copy of Timpa's 911 call in September 2016. Lawyers for the city and county repeatedly refused to release nearly all of the records, citing a continuing investigation.

But lawyers for Timpa’s family obtained the body camera footage through a civil rights lawsuit in federal court, where it remains subject to a protective order.

The footage shows the officers mocking Timpa as he struggled to breathe, according to lawsuit filings.

The family’s lawsuit has been stayed by a federal judge until the outcome of the officers’ criminal case is resolved.