A police officer who was present at Sandra Bland's traffic stop claims that the Waller Count district attorney refused to let him testify on Bland's behalf in front of a grand jury.

Former county judge DeWayne Charleston recorded a phone call with the officer, Michael Kelley. Kelley, the third officer on the scene, told him that he heard Brian Encinia, the arresting officer, turn off his mic and tell his sergeant, “I have no idea what I’m going to arrest her for, but we’ll figure it out when we get to the county jail.”

Bland, 28, was found dead in her cell three days later. While authorities considered her death a suicide, protestors have insisted that Bland was murdered. Kelley told Charleston that when he made clear his attentions to testify, the district attorney Elton Mathis threatened him. “I wanted to testify on Sandra Bland’s behalf and they told me if I said anything they’re going to come after me,” Kelley said.

Mathis vehemently denied these claims in a written statement to the Houston Chronicle. "I unequivocally state that he never approached me, my first assistant, or any member of my staff with any such information," he wrote. "His job was never threatened by me or my staff, and I barely knew who he was before he was indicted."

Recently, an ex-guard admitted to falsifying jail logs just before Bland's death. Listen to Kelley's account below.