After Rolando Penate of Springfield was arrested on charges of selling heroin, the job of making sure it really was heroin went to chemist Sonja Farak at the state drug lab in Amherst. But on the day she made that determination, Farak would later testify, she was zonked out of her mind.

Penate’s defense attorney, Luke Ryan, recounts what Farak told a grand jury.

"'On that day I showed up at work. I began smoking crack,' " Ryan said she testified. "'We had some LSD at the lab, and I decided to take some.' "

On Monday, a week-long hearing began in Hampden Superior Court, delving into the state drug lab scandal involving Farak, who pleaded guilty to tampering with criminal evidence nearly three years ago.

Some defendants with cases containing evidence handled by the lab are seeking new trials.

And now, the judge overseeing the hearings wants to find out not only the scope of Farak's tampering, but also if the former attorney general's office covered up evidence of Farak's long history of drug abuse.

Discovering The Scope Of This Crime Lab Scandal

Over the course of eight years, Farak had siphoned, smoked, snorted and swallowed her way daily through the larder of the state drug lab. Crack, methamphetamine, weed, LSD, ecstasy. She treated it like she were at a Bob’s Big Boy. She piled her plate. It was free for the taking and she took — and cooked — from the lab standards, from police seizures and from her colleague’s work tables.

State chemist Sonja Farak, in an undated photo provided by the attorney general's office (AP)

When Farak was later asked if there was ever a day she was so incapacitated she should not have been at work, she said yes, on Jan. 9, 2012.

"'I was too impaired to drive home,' " Ryan said Farak testified in a drug certification. "She claimed that on that day she couldn’t have possibly operated any of the equipment, she was so under the influence. She has no recollection of being able to use the instruments on that day, but that she said that she performed testing that day."

That was the day Farak -- who turned out to be a drug addict working for a drug lab — certified the drugs in the case against Penate. He went to prison, where he's served five years. The state public defender's office said as many as 18,000 cases in all could be linked to and considered contaminated by Farak.

Defense attorney Ryan, who knew none of this at the time, attempted to obtain evidence from the attorney general’s office, which was prosecuting Farak. Unbeknownst to him, Ryan said, prosecutors had been sitting on key evidence for 22 months while fighting disclosure and accusing him of a fishing expedition.

In Farak’s car, police had found a mental health diary she was keeping about her drug use.

"They did not disclose they had this Service Net Diary card. This was just one of dozens of pieces of paper that indicated that Sonja Farak had a longstanding drug addiction," Ryan said.

At the time of Farak’s arrest, Attorney General Martha Coakley had assured the public that the scale of misconduct was small — unlike that of the chemist Annie Dookhan, a state drug lab chemist who, in an unrelated case, was sentenced to prison in 2013 after admitting she faked drug evidence results.

The misconduct of Farak, Coakley claimed, lasted no more than four weeks. And it did not jeopardize the rights of defendants.

But that was false.

The trail from the mental health notes in Farak’s car led back to evidence that Farak had been abusing drugs in the laboratory as early as 2004. So this was a scandal not of four weeks, but of eight years.

And it only became public after a judge allowed Ryan to see the files.

"There’s no question that highly exculpatory evidence was not disclosed. There’s no question that members of law enforcement, state police and the attorney general’s office knew that they had these materials," he said. "And the reasons for why they weren’t disclosed, I think, remain one of the big questions that just needs to be answered."

'Stunning Testimony' From Former AG's Office Attorney

On the first day of the evidentiary hearings this week, Superior Court Judge Richard Carey said he wants to find out whether prosecutors “intentionally buried important, exculpatory evidence.”

The defense attorneys represent 10 defendants — some of them shackled observers in the courtroom — who want new trials because of Farak’s egregious conduct.

Armed with 800 emails between prosecutors and state police detectives, defense attorneys bore in on former Assistant Attorney General Kris Foster.

"'This is merely a fishing expedition,' " Foster read on the stand. They were her own, now-uncomfortable words from three years ago, when she was assigned to quash Ryan’s effort to find out what was in the files about Farak’s drug use.

Foster continued reading her words to the court: "'There is nothing to indicate that the allegations against Farak date back to the time she tested the drugs in defendant's case.' "

That was not true. And the evidence it was not true was in the file. So why had she said that?

"I was told that everything had already been turned over. So I wasn’t aware of anything in his file," she explained in court. She said she didn't recall who told her that.

Over and over again, Foster — who is just the first in the upward chain of assistant attorneys general to be called — repeated the same line: She was doing what she had been told.

"No, because I had been told that everything that needed to be turned over had been turned over," Foster said.

What about the lead investigator? Had she asked him, since he compiled the file? The answer: no.

"I don’t remember much more other than being told I didn’t need to see the file, that there was nothing in it, that I should just go with that," she said.

“They were my superiors,” Foster said in explanation of why she did not even look into the file to verify that what she told the court was true.

Indeed, she admitted to artfully misleading the judge by suggesting she herself had reviewed it.

"This is really stunning testimony," said Matt Segal of the Massachusetts Civil Liberties Union. "What she admitted to is that not only had she not reviewed the entire file. She had not reviewed a single page of it before sending that letter to a judge."

Defending the state, a team of assistant attorneys general have tried to undo the damage. They sought to establish that, in their words, Foster had not tried to mislead the court or to withhold evidence. They've said that no filings were made with the intent to hide particular documents in the office's possession.

Yet the state's attorneys in Springfield also have tried to isolate Foster from her former superiors in the AG's office. Their questions portrayed here as inexperienced, untrained and guilty of poor practice.

When asked if she would do the same thing again, Foster said she would have looked at the file herself.

But Foster has pointed to her superiors. And some of those many emails between prosecutors and detectives suggest Foster's superiors were discussing what to do with the evidence they had not turned over even as Foster said they were assuring her that everything had been turned over.

Thousands of cases and their outcomes await the judge's findings.

And the investigation is moving up the chain.