Ms Bland was found hanged in her jail cell on 13 July, three days after she was arrested during a traffic stop.
The Harris County medial examiner ruled the death a suicide. But Ms Bland's family has rejected that determination and the Waller County district attorney has said her death is being investigated as a murder.
On Monday a sheriff's official gave the New York Times a timeline of Ms Bland's last few hours. At 6:30 am on 13 July she turned down a breakfast tray and was found dead around 9 am.
A surveillance video shows that in the 90 minutes before she was found hanging, there was no movement by jail officials in the hallway leading to her cell.
See the video below for the part of the surveillance footage released by authorities.
“This investigation is still being treated just as it would be a murder investigation,” the Waller County district attorney, Elton Mathis, told the Times. He said the case is likely to be turned over to a grand jury expected to be impaneled in August.
Ms Bland's family has said they do not believe she would have killed herself and have called for an independent autopsy.
The Rev. David Madison, president of the A.M.E. Ministers Alliance in Houston, has joined family members and other protesters in calling for a Justice Department investigation
“We’re not accepting the report of death suicide,” the Rev. Madison said. “Sandra Bland had just moved from Chicago to Houston to start a new job. You don’t come all the way to Houston just to kill yourself.”
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