In the annals of wrongful convictions, there is nothing that comes close in size to the epic drug-lab scandal that is entering its dramatic final act in Massachusetts. 
 
 About 23,000 people convicted of low-level drug crimes are expected to have their cases wiped away next month en masse, the result of a five-year court fight over the work of a rogue chemist. 
 
 "It’s absolutely stunning. I have never seen anything like it," said Suzanne Bell, a professor at West Virginia University who serves on the National Commission of Forensic Science. "It's unbelievable to me that it could have even happened. And then when you look at the scope of the number of cases that may be dismissed or vacated, there are no words for it." 
 
 Annie Dookhan was arrested outside her home in Franklin, Massachusetts, in 2012. Bizuayehu Tesfaye / AP, file 
 
 The dismissals will come in the form of filings from seven district attorneys ordered by the Massachusetts Supreme Judicial Court to decide who among 24,000 people with questionable convictions they can realistically try to re-prosecute. 
 
 Their answer, due by April 18, is expected to be "in the hundreds," a spokeswoman for Middlesex County District Attorney Marian Ryan said this week. An exact number was not available because the prosecutors are still working through the list, the spokeswoman, Meghan Kelly, said in an email. 
 
 The development was first reported by the Boston Globe. 
 
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 The prosecutors didn't want the scandal to end like this. They fought for a way to preserve the convictions, and leave it to the defendants to challenge them. 
 
 Civil rights groups and defense lawyers argued for all the cases to be dropped, saying that was the only way to ensure justice. 
 
 The state's high court chose its own solution, ruling in January that district attorneys should focus on a small subset of cases it wanted to retry, and drop the rest. 
 
 A special drug lab session handled motions by drug defendants whose cases were handled by chemist Annie Dookhan. Pat Greenhouse / Boston Globe via Getty Images 
 
 It has taken five years to get to this point, longer than it took to discover, prosecute and punish the chemist, Annie Dookhan. She worked at the William A. Hinton State Laboratory Institute in Boston for nearly a decade before her misconduct was exposed in 2012. She admitted to tampering with evidence, forging test results and lying about it. She served three years in prison and was released last year. 
 
 By then, most of the people Dookhan helped convict — most of whom pleaded guilty to low-level drug offenses based on her now-discredited work — had finished their sentences. 
 
 Is not entirely clear why Dookhan, a Trinidadian immigrant mother, felt compelled to change test results on such a massive scale. She was by far the lab's most prolific analyst, a record that impressed her supervisors but also worried her co-workers — a red flag that went overlooked for years. She seemed driven to stand out, even if it mean lying, former colleagues have said. She also maintained friendly relationships with prosecutors, even though her role was to remain objective. 
 
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 Many of those convicted through Dookhan's work likely did commit the offenses, but many did not, defense lawyers say. All of them are now burdened with dubious convictions that have made it difficult to find jobs and housing or to obtain student loans, the lawyers say. Some defendants were convicted of more serious crimes, and the drug convictions were used to stiffen their sentences. Non-citizens have been threatened with deportation. 
 
 Civil rights advocates say the case has exposed the folly of aggressive enforcement of low-rung drug offenders, many of whom are addicts in need of treatment. 
 
 "It's a soup-to-nuts indictment of the war on drugs," said Matthew Segal, legal director of the American Civil Liberties Union of Massachusetts, whose lawsuit led to the supreme court's ruling. "These scandals happen around the country because our war on drugs is based on cutting corners." 
 
 The William A. Hinton State Laboratory Institute, which houses the Massachusetts state drug lab. Steven Senne / AP, file 
 
 The reliance on forensic science in the criminal justice system has improved policing and prosecutions, but the misuse of science has also fueled wrongful convictions, researchers say. Drug labs play a distinct role in that machinery. 
 
 Lab scandals have undermined thousands of convictions in eight states in the past decade, according to data maintained by the National Association of Criminal Defense Lawyers. Critics say forensic chemists feel a duty to help prosecutors rather than remain neutral. And they point out that many labs — including Hinton when Dookhan worked there — lack professional accreditation or proper protocols to prevent and detect misconduct. Some of her superiors have lost their jobs for failing to notice or report her misdeeds. 
 
 "This drug lab scandal is another example of why the criminal justice system needs to reform its approach to forensic science," said Dan Gelb, a Boston attorney who helped write an amicus brief on the Dookhan case for the National Association of Criminal Defense Lawyers. "Labs shouldn't be an extension of law enforcement." 
 
 Former Massachusetts state chemist Annie Dookhan before entering a guilty plea in November 2013. David L. Ryan / Boston Globe via AP, file 
 
 Because of the system's reliance on plea bargains to keep cases moving, defendants often don't have a chance to challenge results from drug labs, Bell added. 
 
 That's become a big point of discussion at the National Commission of Forensic Science, she said. But the commission, which was formed by the U.S. Department of Justice in 2013, is facing an uncertain future, with no clear message from the Trump administration if its work will continue to be funded, Bell said. 
 
 The Dookhan case awakened Massachusetts to the crisis, Bell said. 
 
 But the end of the Dookhan saga will not bring the end to Massachusetts' problems. 
 
 That's because it is dealing with a second scandal, at a second lab, this one the result of a chemist who admitted to doing drugs — including an array of substances submitted as evidence — while on the job. 
 
 Thousands of convictions in that case are now in doubt. ||||| Annie Dookhan served three years in prison on perjury and evidence-tampering charges before her release last year. 
 
 The vast majority of drug cases potentially tainted by former state chemist Annie Dookhan will be vacated by mid-April, with just a few hundred convictions out of 24,000 remaining on the books, according to district attorneys. 
 
 The prosecutors have been working on a 90-day deadline issued in January by the Massachusetts Supreme Judicial Court to produce shortened lists of Dookhan convictions they believe must stay in place and are getting close to concluding. 
 
 “Without putting numbers on it, it’s in the ballpark that the court was looking for,” said Robert J. Bender, a Middlesex County assistant district attorney, at a March 16 meeting with SJC Justice Margot Botsford. “Hundreds of cases, not thousands of cases.” 
 
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 Even if district attorneys keep 1,000 of the convictions intact, that would be less than 5 percent of the statewide total of approximately 24,000. 
 
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 The estimate includes all seven district attorney offices that handled Dookhan cases — the Bristol, Essex, Cape & Islands, Middlesex, Norfolk, Plymouth, and Suffolk districts, Bender said. 
 
 Dookhan, who was responsible for testing drugs in about 40,000 cases at the former Hinton laboratory in Jamaica Plain from 2003 to 2012, admitted to more than two dozen charges of tampering with evidence and fabricating results. She served three years in prison, for perjury and evidence-tampering, before she was released on parole last year. 
 
 Since Dookhan’s misconduct came to light in 2012, defense advocates have called for erasing convictions in any case she touched. They argued that the scale of her tampering made case-by-case appeals unworkable because the process would require far too many public defenders. 
 
 The January SJC ruling pushed prosecutors toward dismissing Dookhan cases in bulk, but declined to wipe all defendants’ slates clean. The court gave DAs in all seven districts an April 18 deadline to determine which convictions to dismiss and which to keep. 
 
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 The court made clear that prosecutors were to “reduce substantially” the number of defendants who might challenge their convictions because of Dookhan’s crimes. 
 
 It is not the “global” dismissal defense advocates sought, but some said they were pleased that as many as 95 percent or more of Dookhan cases may be vacated. 
 
 “Even the possibility that this might happen means that anyone who cares about criminal justice in Massachusetts ought to be paying attention to April 18,” said Matthew Segal, legal director of the American Civil Liberties Union of Massachusetts, whose clients’ lawsuit led to the SJC ruling. 
 
 The court reserved the right in its ruling to dismiss additional cases if the prosecutors do not dismiss enough cases. 
 
 But with less than four weeks until the deadline, prosecutors predict both the court and the defense will be satisfied with how short the lists of remaining convictions will be. 
 
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 “I think the court will be happy with the numbers,” said Susanne M. O’Neil, a Norfolk County assistant district attorney who also attended the meeting. 
 
 Prosecutors in all seven districts declined comment on how many defendants would be on their dismissal lists, because some cases are still under consideration. 
 
 “We are in the middle of an arduous review of our Dookhan cases and are unable to give you a progress report at this point,” said Carrie Kimball-Monahan, spokeswoman for the Essex district attorney’s office. 
 
 Essex County has approximately 4,200 cases affected by Dookhan, second only to Suffolk with 8,600 cases. 
 
 In January, a public defender with the Committee for Public Counsel Services warned that any caseload above “four digits” would strain the agency’s resources and budget considerably. Nancy Caplan, who heads the CPCS unit that represents Dookhan defendants, said at the March 16 meeting that keeping the number of cases low “would make CPCS very happy.” 
 
 Caplan also told attendees at a legal workshop on Friday that her office anticipates the maximum number of non-dismissed Dookhan cases will be 1,000. 
 
 The unanswered questions are which convictions will remain in effect and whether individual Dookhan defendants with standing cases will appeal in court. 
 
 According to one data analysis conducted by the ACLU of Massachusetts and cited by the SJC, a majority of Dookhan defendants were convicted on drug possession charges alone. Approximately 90 percent of convictions were misdemeanors or minor felonies for which defendants had already served their time, that data indicated. 
 
 District attorneys say their top priority in reviewing cases is public safety, and they might try to preserve some convictions under non-felony charges in lower courts if that means they can keep a violent offender behind bars. 
 
 But prosecutors face a tough evidentiary burden to keep convictions in any cases handled by Dookhan. 
 
 For all undismissed cases, the district attorneys must certify they could prove the defendant’s guilt without using evidence that was tainted by Dookhan’s dubious testing or testimony. That would be particularly difficult for older cases in which drug samples were destroyed years ago, or cases where the defendant pleaded guilty only after receiving results from Dookhan’s analysis. 
 
 All defendants whose convictions remain in place must be notified by mid-May, under the SJC’s order. 
 
 Shawn Musgrave is an investigative reporter based in Boston. He can be reached at shawnmusgrave@gmail.com
– It's been five years since former Massachusetts State Police chemist Annie Dookhan pleaded guilty to tampering with evidence while working on tens of thousands of criminal cases. But 24,000 people left with questionable convictions as a result of her fraud are still waiting to see if their names will be cleared. Not for much longer, though. The Massachusetts Supreme Judicial Court has until April 18 to decide who among the group will be re-prosecuted without evidence touched by Dookhan. And though prosecutors are still deciding on cases, a rep for the Middlesex County District Attorney says the number of convictions that will be kept on the books will likely be "in the hundreds," per NBC News. In other words, more than 95% of them will be vacated, reports the Boston Globe. "There are no words for it … It's absolutely stunning," says a member of the National Commission of Forensic Science. While this means some who did commit crimes may see their convictions overturned, it also means those wrongfully convicted will finally get justice, including non-citizens who've been threatened with deportation, defense lawyers say. The ACLU of Massachusetts says that about 90% of the convictions are for misdemeanors or minor felonies, usually involving drug possession, and that most defendants have already finished their sentences. Dookhan herself was paroled last year. (Click for more on the scandal.)