Updated

The death of a man who was restrained by an off-duty Texas sheriff's deputy and her husband during a late-night confrontation outside of a restaurant was ruled a homicide on Tuesday, and local authorities are asking state and federal departments to help investigate the incident.

John Hernandez, 24, died of lack of oxygen to the brain caused by strangulation and chest compression, according to the Harris County medical examiner.

Investigators said the May 28 altercation started after Terry Thompson, the husband of Harris County deputy Shauna Thompson, became offended when he allegedly saw an intoxicated Hernandez urinate outside the Houston-area restaurant. They said Shauna Thompson helped her husband restrain Hernandez and that the incident ended with a motionless Hernandez being rushed to a hospital.

He died three days later. The deputy has been placed on administrative leave.

Cellphone video that a bystander recorded of the incident has been released by the unidentified person's lawyer and posted on local media websites. The footage shows a man lying on top of Hernandez. Jack Carroll, the attorney for the person who recorded the video, said the man restraining Hernandez used an illegal chokehold.

Sheriff Ed Gonzalez said he has asked the Texas Rangers and the U.S. Department of Justice to assist in the investigation.

In a statement Tuesday, the sheriff's office also said it has presented the findings of its investigation to the Harris County district attorney's office.

Randall Kallinen, an attorney for Hernandez's family, said authorities should make arrests based on the medical examiner ruling and the bystander-recorded video of the confrontation. Scot Courtney, an attorney for the Thompsons, said Hernandez was the aggressor.