Four Assistant District Attorneys Tuesday were ordered to testify to the grand jury and, to make it worse for the DA, a special independent prosecutor is about to be named.
The ADAs all tried DWI cases and likely know if supervisors downplayed faulty DWI tests. The grand jury is still meeting in secret, but it's becoming clear they are zeroing in on a possible cover-up within HPD or the DA's Office.
What is happening inside a Harris Co. Grand Jury room this month cuts right at the heart of how the DA prosecutes cases.
"This could be catastrophic. Anyone who's been arrested involving these mobile vans could have their cases overturned," said KTRK Legal Analyst Joel Androphy.
With four ADAs and a current judge called to testify, it's clear the grand jurors want to know what prosecutors knew about potentially bad DWI evidence, when they knew it and what their bosses told them to do about it.
"It's not OK to cover up unreliable evidence; period," said Tyler Flood, a DWI defense attorney.
On Monday, Harris Co. District Attorney Patricia Lykos told Eyewitness News she never knew about the problems with the BAT vans until they came out in open court in July.
"The Houston Police Department Crime Lab has never notified us of any questions or any issues with respect to the BAT vans, and that includes as of today," Lykos said.
And that's true if you listen very carefully. Officers from the crime lab never came to her office. But other police officers spoke up months earlier. She didn't tell us about that.
In court testimony, one police officer testified he knew of issues a year before and told prosecutors about them more than once without questioning the admissibility of the evidence.
The lawyer for the whistle blower in the case says the DA isn't telling the whole story.
"She should've kept her mouth shut," said attorney Chip Lewis.
But Lewis says the DA isn't the only one who should be concerned; he's convinced this grand jury will want answers from HPD as well.
"It's clear to me that HPD broke the law. Whether it's a civil law by retaliating on Amanda Culbertson or the criminal law of official oppression, I will let the grand jury make that determination," Lewis said.
With the addition of a special independent prosecutor, that grand jury investigation just got a lot more serious.
"You start with people who were the messengers, then work up to the supervisors and work your way up to determine if there was a cover-up," Androphy said.
Amidst all the claims of cover-up, none of it's been proven and the DA continues to insist they did nothing wrong.
The special prosecutor has not been named, but once that person is on the job they will help the grand jury figure out if a crime has been committed.
Here's a look at a timeline in the BAT van investigation:
Our 13 Undercover investigations exposed maintenance problems with the BAT vans back in March.
Emails we uncovered about the Breathalyzer accuracy prompted attorneys to challenge DWI cases connected to the vans.
A hearing was held in July where Culbertson openly testified about the lack of response to the BAT van issues.
In October, Harris County commissioners terminated a contract with Culbertson's current employer to provide DWI testing in the county.
Last Friday, Eyewitness News first reported that the grand jury appeared to be investigating how the DA's Office and HPD handled reports of the BAT van problems.
Today, we confirmed four prosecutors have been subpoenaed in that investigation.